Oh, I've lost count of how many times I've asked T-nex about this.
She's told me roughly what they're about, basically what she said above but a bit more detailed, although she refuses to tell me anything more. I'd imagine Non-main is for RPGs not conencted with the Main RP (ie. all the current Rps go to Non-Main (except W@RF T-Nex hinted that W@RF could be connected with the main RP)) while Info is for things like the character profile threads, rules, off-topic RP discussion, clarification of current RP events, an RPG timeline etc. At least that's what I'd guess at.