FastChat Rig (or similar)

I am new here. I have an older i7 (6th gen) CPU, 64GB Ram, 512GB SSD. I want to turn this into a FastChat or similar rig. I ordered two RTX 4090 OC TI’s to run on here.

  1. Regarding the hardware, would this be optimal, or should I buy a newer CPU/MOBO/RAM combo?
  2. Should I install Linux directly on this machine?
  3. Do you have step by step instructions on how I can successfully get this rig going that includes installing the correct drivers for the video cards?