Is it legal according to the TOS and TOU if you have an account on one device, but you never use it on that device, can you use UDiD faker or something to access that legal account remotely?
No. What you can do is, access that account from PC. Accessing many accounts from one device (unless a PC with many iDevices linked) is a breach against ToU. By "device" I refer to Android/iDevice.
No if you want to access that account you will need to transfer it to another device or link it to PC.
I just noticed an interesting fact. Your regen time resets to the moment you use a xtal. Can anyone confirm that or am I just imaging it?