The safe is the ligher-colored sliding door on the shelf.

Around the room are 5 books of different colors: Green and turquoise on the bookshelf, yellow in a drawer below it, violet on the table, blue below the PC screen.

Notice the painting on the wall with the different colored stripes.

Book number in the position of the stripe is the code needed for the safe.
Enter the wrong code first for an achievement.
Note that a 6 can also be a 9.

The code is 9623

with the remote from the safe, you can start up the TV. It displays a QR code which leads to https://imgur.com/glzEcqt

You want to turn on the computer, so take a note of which switches connect the computer (screen with tower) to the battery. Those are the numbers 1, 4, 5 and 6

Besides the fire place is a grey panel on the wall, interact with it to reveal a series of switches.
Flip only the switches connecting the battery to the pc and press the red button.

Go to the PC and press the big white button on the tower to turn it on.

The unlocked computer will play a series of morse signals when you interact with it.
Those are ··-- ···-- ----·.
Translate them using the handy morse alphabet to get the code for the sofa, 2396
Make sure to interact with it again after unlocking.

Once in the cellar, the gate won't budge and the panel to the right of it tells you you didn't pass identification.
Grab the crowbar to the left of the gate behind the wooden trash and return back the way you came.
At the stairs, look for the illuminated face.
Grab the mask and return back to the scanner, use it and use the gate.

On the left side of the broken minecart tracks hangs a chain you can pull. doing so will reveal a hidden section at the end of the tracks that you can jump up to. Hidden there is yet another password panel.
On the minecart tracks, nearer where you came from, you'll notice some carved in letters.
In he order from where you came they are EPECSA
Now you have to order them in a way that makes sense, ESCAPE, to get the code for the hidden panel.
After entering it, return to the end of the minecart tracks use the two big stone slabs right next to it to reveal a hidden passage

I don't think so. it has a code panel but I found no hints for it. Write a comment if you know a way