Hi,
TT RGB Plus only works in Windows, the profile and programs are stored in your hard drive.
If you go with Linux, the products will work as normal, LED lights up no problem, but the software wont activate in Linux and you cant control the products in TT RGB Plus.
Yes, you can fit the fans, please see attached fan support list.
For controllers connection, you will need to use 4 controllers and 4 molex cables, and here is our suggestion, (2 x trio 20 + 1 x controller + 1 x molex 4pin cable), (2 x trio 20 + 1 x controller + 1 x molex 4pin cable), (4 x trio 12 + 1 x controller + 1 x molex 4pin cable), (1 x floe riing 360 aio + 1 x controller + 1 x molex 4pin cable).
Our AIO already have thermal grease applied, you can change a new one if you like. No aluminum in water block, and screws have no contact with coolant in AIO.
You can check pump speed in BIOS, make sure it's still running.
Yes, the first controller connects to on board USB 2.0.