OP says he gets into long slugfests but also says he's never seen or heard of commanders in this game. I don't think playing long matches in any recent RenX history would have no commanders if server has a decent population. It sounds like what he wants added is already in the game but hasn't actually played the game.
Does not seem your GPU is being used as discrete renderer. The error is related to GPU stuff, recently solved it by forcing discrete GPU usage. Can you share where you're setting that at?
IIRC we had someone on the team who did some performance optimizations and he noted something about how the mouse movements (maybe related to high polling rate) creates bad stutters and that the engine doesn't lock the mouse cursor to the center of the screen. It may be related to the Steam overlay so I'd suggest trying to disable the overlay in Steam then try launching it again.
Whitelisting service for official servers can't be connected to or it's not connecting with the same IP as the game is using. Can be manually corrected via Discord if you make a support ticket.
In the game folder/UDKGame/Config/
copy an existing CNC-WhateverMap.ini, rename it to your map name and change the MapName and FriendlyName and the header to whatever your map is called.