Fallout: New Vegas

This quest is the Legion endgame quest and unlocks other legion quests, et tu brute and arizona killer.

The quick quest details are:
Kill Mr House
Befriend/Defeat the Boomers - by helping them you gain a water breather which becomes useful later on when entering Vault 34
Blow up the Brotherhood of steel
-- Return to Caesar to activate the Et Tu brute? quest
Here you have to cure Caesar's tumor depending on your skill there may be alternatives however I didn't have a high medicine so I had to get surgical equipment from New Vegas medical center and retrieve parts from an auto doc in vault 34.
Return to Caesar to cure him (you can kill him but this wasn't the path I took).

-- This Completes Et tu brute
-- Speak to Caesar to activate the Arizona killer quest
Meet up with cato
Prepare for the assassination
Let cato know you are ready
assassinate the target - completes Arizona Killer
get back to Caesar to complete render unto Caesar

Personal experiences with this quest

You can blow up the Brotherhood bunker by pickpocketing the three security keys from three main people in the Brotherhood, namely Elder McNamara, Head Paladin Hardin and Head Scribe Taggart. You can then get the self destruct terminal password from the console next to the self destruct console itself. Once you begin the sequence the brotherhood become hostile towards you so make sure you are ready to run or fight.

With regards to vault 34, it is heavily irradiated (1 rad/sec for the entire time you are in the vault) so be sure to bring plenty of rad-x and radaway, there is a safe with a ton of them inside the vault but this requires level 50 lockpick to open. The vault is also teaming with ghouls and glowing ones so bring decent weapons.
If you have the water breather given to you by the boomers bring it along as you need to travel under two flooded corridors to retrieve pass keys to get to the auto doc.

After reporting to cato he gives you an NCR uniform and goes to the dam, when you're ready put on the uniform as only the NCR rangers can see through this disguise and proceed to the dam yourself.
What I did:
I had a good sneak level when getting to Arizona Killer around 70 so this may not work for all but I simply sneaked pass the rangers to tell cato I was ready, I then went and hid behind a large structure directly across from the Hoover Dam visitor center where I was hidden from rangers but could see the platform your target stands upon.
I then sniped the target and got the hell out of there as quick as possible as the NCR become hostile, by standing here to snipe the only NCR member within gun range is the ranger patrolling in front of the visitor center entrance this made getting out of gun range and far enough away to fast travel pretty easy.

WARNING:: Change out of the NCR uniform before fast traveling back to the fort or all the Legion soldiers will attack you as soon as you get there

if you want to speed through these missions the stealth boy is you best friend.

most of you will know the area pretty well due to previous missions. i will post the quickest way i did these missions

MR HOUSE
with mr house i just ran up to the penthouse. the robots are rubbish aim and dont do too much damage so you can just sprint past them to mr house and then do what you want.

BOOMERS
boomers talk to the guy outside boomer base he will tell you the best route (however you will get hurt still) once inside you have a choice i suggest befreinding them as i didnt like the thought of killing the leader and tehn trying to run out of a base with rocket obsessed weirdos. all you need to do is clear the ants out of the power station and then fix the power station. if you have 50 science and are friends with the people at helios then you can repair the dishes better then before.by getting spare parts from helios. if they dont set you up for the next mission talk to the brat in his cabin and get them to tell you bout there past that should be enough. once thats done you talk to the old lady boss person (Pearl) and she will you to talk to the old man boss person(Loyal)(getting technical) and he will tell you to go to the lake and find a bomber talk to Jack and he will ask you to get a vacume cleaner (if you have a high enough science(45) you dont have to get the vacume cleaner). head to the lake put the rebreather on (the one that jack gave you) place the ballests then follow the marker to the shore and switch to the detornator and bring it up. head back to the boomers get a pat on the back.

BROTHERHOOD
first you need to kill the ranger he will be hostel as you are working for ceaser. come back and then the real fun starts.
brotherhood i pickpocketed the three security keys from Elder McNamara, Head Paladin Hardin and Head Scribe Taggart. then i remebered the shortest route out of the bunker. once the self destruct is set stealth boy up and sneak out no one should see if you have light armour on. if you are waring heavy armour take it off and walk out naked with a stealth boy( like a phantom nudest)

WHITE GLOVE SOCIETY
white glove society. this i found irritaiting as the game kept crashing as i went up and down the lifts. but mostly its a lot of talking and walking about if your speech is high enough (38 speech) the idiot in the freezer wont complain. the only fun bit is getting idiot number two into the skip by the shack. with the black widow perk i told him to get undressed and climb in this made me chuckle. i cant really say much about this section but here is a better walkthrough of it here:http://fallout.wikia.com/wiki/Render_Unto_Caesar and here http://fallout.wikia.com/wiki/Beyond_the_Beef

VAULT 34
vault 34 i fought my way to the entrance (past the golden geckos) before i entered i put on a hazmad suit (well space suit) and a stealth boy then crept to the clinic now im going to try to remeber how to get to the clinic.
as you enter the main vault door go into the main room and turn right(dont cross the bridge) then head down the stairs to the floor below. then go through the broken door thats trying to close and head right open another door and go down more stairs.
you should be looking at a load of signs saying the clinic is to the left however the way is blocked so go right and follow the corridors until you get to a junction follow the left corridor (pretty much straight ahead) follow this corridor round to the left and the clinic should be ahead of you when i got there as i was sneaking the door was open (which could be why people have needed to go find the key card) go in there and there should see the auto doc over by the back wall. retrieve the parts and leave the way you came in.
This might not be completely correct as im trying to do it from memory i suggest saving just outside the vault just incase i am wrong.
Serviceace said you need a pass key but i dont think i picked one up it could be that the game glitched and i opened a door that i shouldnt have.
minimum number of stealth boys needed is 2 one to get to the clinic and one for the trip back. i suggest three as it is a bit neverve racking walking past the ghouls thinking my stealth boy could run out any minute and i dont have another one.

KILL THE PREZ
killing the prez as i enter the damn i went in the first door on the right(near the ranger with the dog , wait till he walks away from the door) once in the visitor center you can head to the cuboard under the stairs and pick up an ncr engineer suit. put it on then head up the stairs and outside to talk to cato.(note you can hack the computer (50 science required) in the downstairs visitor center this will tell you that an engineer "nudge nudge" need to look at the prez chopper. also if you have this ability you wont need to be an engineer as you can reprogram the chopper to crash on the way out.) once you have spoken to cato if you havent reprogrammed the chopper and you have 50 explosive you can ask for the bomb.
walk back up the stairs and head round to the left of the building (watch out for the ranger patroling along here) walk past the ncr guy and climb the ladder now you can attach the bomb to the chopper and climb back down. when the chopper takes off it blows jobs a gooden.

there are more ways of doing this for info check
http://fallout.wikia.com/wiki/Arizona_Killer
and for brain tumour help
http://fallout.wikia.com/wiki/Et_Tumor,_Brute%3F
and for the other bits
http://fallout.wikia.com/wiki/Render_Unto_Caesar

this should be all you need to know if the solution is no good tell me why and i will try to fix it happy hunting

the video below gives you bit of a clue to the layout of vault 34. the guy does faff alot but the room he enters at 6.17 is the clinic. i suggest skipping to 3.05 as before then is nothing useful.the room he is in is the cafeteria which you enter right at the the begining of the vault.
7.07 he finds the auto doc.

***SPOILER WARNING***







This achievement is unlocked in the end-game, following the orders Caesar gives to you, which first involves defeating House, either dealing with or eliminating the Boomers, and ultimately, blowing up the Brotherhood of Steel Base at Hidden Valley and assassinating President Kimball. To blow up that base, you need to go down to the reactor and activate a self-destruct terminal. It is a very hard hack so be sure to raise your science passionately as you go about.

You then have to go through perhaps one of the most hideous vaults in the game, Vault 34, to find an Auto-Doc. Be sure to read the Fallout Wiki for more details.

You unlock the achievement as you accept the final quest: Veni Vidi Vici, where there is no going back once you accept.