At my previous job we did something similar for a museum. We only did 2 walls but the principal is still the same.
GTX1080 should be fine. Might need two and a few extra X4's/Tripple Heads.
We used mirrored projectors and hid the projectors above the drop ceiling (left an artistic gap between the wall and ceiling, having the gap go up 3 feet). Here's a thread on using those types of projectors: http://www.avsforum.com/forum/68-digita ... irror.html
It all depends on how much space your projectors take up on the wall. That determine the amount of hardware you need.
You can have windows autoboot without a login, you can even have Resolume be setup as a startup item, loading whatever cop you want.
In order for it to play from startup, you'll need to install and program a keystroke program (ie. have the program start on the login, then have it wait 3-5 min, then tell it to use whatever keystrokes you want. assign those keystrokes to the keyboard mapping within resolume)
I would highly recommend making your content a single file (for the entire resolution of the room) and doing a lot of fine tuning in your output slices and edge blending. This would ensure that all your screens are playing in sync, rather than multiple files for multiple projectors. after some time, they might get a few frames out of sync.