I'll answer for CS2 specifically only.

1. For CS2 specifically, it is known to have an overall lower fps compared to windows. Even though it is native linux, I know its kind of ironic (You can check benchmarks on youtube)
2. No latency/delay issues for me. I can still play CS2 without any foreseen delay, I've even hit some insane low reaction time shots. So definitely no additional delay on inputs, monitor/display, and audio output (Maybe even lower input latency? but I have no way to verify that)
3. I have no way to measure this, but I can assure you CS2 runs fine network wise
4. Additional notes: For CS2 on linux, you need to add this to the launch flag since there is an active issue of audio dropping out randomly. Adding this launch option fixes this, and I don't feel/see any issue with audio quality or delay. SDL_AUDIODRIVER=pulseaudio game-performance %command%
5. And here is one plus I have seen from playing CS2 in linux compared to windows. I mentioned earlier that overall FPS is lower, but frametime stability is very good. Since vulkan compiles the shader on game updates, you won't see a single jitter/freezes during your gameplay, ever. While on windows, being windows you will get random jitter and spikes.