I helped do something similar for Insurgency, although the end result wasn't as good as I'd hoped for.
Something else we tried, for our community servers, was to have events where we turned on global voice and ran in-game training directly.
We used some mods to allow things like instant respawning, kit changes, and ammo updates so that players could try scenarios using the different tools and mechanics.
We logged the questions, recorded everything, and distilled it down to a series of 1-5 minute videos.
Ideally, we were looking to make levels to demonstrate these things, but there simply wasn't enough time to do it all.
I see you guys have an older campaign mode, putting a series of levels as a "campaign" of lessons, with cues and situations to try these concepts in game, would be a really nice feature for me as a new and overwhelmed player.
Putting all the info down is the first step, the doc and the wiki in general have been really helpful for raw information for me.
But if I had a way to learn by playing, rather than watching and then trying it in Skirmish or in a live game, would open this game up significantly for new players.