Short answers:
- It is possible.
- PCs are good at routing. Switching is for switches. Suboptimal results are to be expected from high-speed switching on a PC.
- If you have the resources to run an iSCSI share for a game library, you should be able to afford a 25G switch. (Mikrotik CRS-510?)
- You won’t get very far here by insulting those who try to help.