Not required for me but might be wise to change the coop runs to allow more than just 2 players to be inserted like the Main Campaigns and All Campaigns runs.

Just something to bring up.

Can't say that I agree with allowing cosmetic changes such as custom skins. You could very easily replace enemy skins with very bright colours, so that they stand out while doing runs (e.g., bright pink hunter, springgreen smoker, etc). Would bring a somewhat silly advantage to speedrunning the game over unmodified versions.

Currently there isn't any rule set for whether you can kick the AI in solo and coop runs, 

Just to bring awareness on kicking bots you can do this in solo runs (official servers included) and local hosted / user owned (rcon commands) servers for coop.

L4D 1 runs currently don't kick bots and kill them at the start of each map (difficulty votes used). I personally would like to keep this for consistency over the series.

However I would like other runners to post on their thought and what they would like rules wise for the AI. This is to ensure I don't just set rules to suit me.