The Good Life

A fairly easy achievement but there are a couple of tricks/puzzles that hopefully this solution can help with. You’ll have to play through a few other missions to get the Route A, B and C missions – I didn’t keep track but I was around 7 or 8 hours into the game (and I got sidetracked a bit). Edit: If you mainline the story missions, you can get to the Route missions in about an hour. You’ll unlock all 3 'Route' missions at once and once unlocked you can choose which order you want to do them.

Spoilers have been avoided to a degree but consider yourself warned.

Background Check 101
Go to the Town Hall and use either of the marked doors to enter. A scene plays to officially begin the Route C missions.

The Heritage of Rudman White
Go to the Town Hall. After a conversation, talk to Rita Barrett for more conversation.

Line up three gnomes on the path to the White residence
You need to find all 3 and carry them to the marked spot, which is the White Estate Approach. As you approach the marker you will automatically place the gnome you are carrying. This is timed – if you fail to have placed all 3 gnomes by the end of the day, your progress will reset and you’ll have to start again.
On the opposite side of the road to the Town Hall, there is an open gate leading to a garden with a trampoline in it – the gnome is near the front fence by some pink flowers. This is the Macaulay Residence.
Go back to past the Town Hall and head into town. Just past the gate to the Macaulay Residence you’ll see another open gate. The second gnome is visible from the path. This is the Yi Han Li’s and you may have already been here for a Golden Egg.
The final gnome is much easier. Leave the White Estate Approach and look a little to the left. You should immediately spot the third gnome on the side of a driveway opposite.

To the White Residence!
Go to the gate and talk to Norlock Homeless. (Not sure if your answer matters – I chose Elizabeth and things progressed).
Looking at the gate, turn right and follow the wall around the corner. Proceed halfway along this side of the perimeter fence and you’ll see another wall running off to the right, with a gap to the perimeter wall. Switch to the cat and look on the far side of this second wall – there is a climbing point a little way along. Use this to get to the top of this wall.
Turn right towards the house. Not sure if you need to run (I did) but press to jump when you reach the end and you’ll clear the gap and get inside the perimeter fence.
Turn right and when you reach a wall look for a cat interaction point in the corner. A little further along, jump over the obstructions. Around another corner, look for a cat interaction point on the building wall. This gets you to the roof. From there, simply drop down to the front of the building, approach the gate and interact to open it.

The Secret Royal Bloodline
Head to the Berryman Residence, which is marked.

Weird Voice
After the scene, head left of the house to find John Berryman in the garage. He’s hungry, so head back to Mushroom and Evens in town. Buy a Creamy Mushroom Pie and carry it back to John.

To the Southern Lake!
Before you proceed, be sure you own the “Old Telephoto Lens” which can be purchased from the camera shop in town for $786.45 (at least, that was my price).
If you’ve explored and unlocked some shrines, you might be able to visit a shrine and teleport to the Lake Sutrains Shrine, which is to the South-West. Otherwise, run or ride down there – it’s marked.
After the scene that plays when you arrive, walk over to the easel nearby. Look directly at the painting, with your back to the lake. You should see the scene in the painting above it, specifically a tree that looks like a giant head. Hold to frame “Giant???”. Press to switch lenses and find the giant’s head. It should change to “Giant”, so take a picture.
Talk to Norlock Homeless nearby and hand over the Giant photo.

To the White Residence Again!
Make your way back to the White Residence and talk to Homeless once more. Get through a long conversation/scene.

Curtana, Blade of Legend
Make your way to the marked location, over to the South-West. A scene with Homeless plays out when you arrive at the gate.
Activate the nearby shrine if you want, then proceed forwards where you’ll find Homeless at the next archway. Transform to a dog and talk to him. At this point unlock this achievement.