All of your questions, while it'd be nice to have them answered, don't need to be answered before launch. There's some aspects of the game that can go unanswered, not to mention (like someone said earlier) all of your questions will be answered on November 6th. There's no reason for 343i to blow their load two weeks before launch just to get a couple fans to simmer down.
I suppose it'd be nice to "plan ahead", but why would it matter? If you knew these questions, you'd still have to go in yourself, get aquatinted with the interface, and learn it on your own - the only good answering these questions is solidifying that they exist, for example certain Forge options.
About your "incentive" to play Reach, you shouldn't need an "incentive" to play a video game. It's just a video game, which is meant to be fun and entertaining. Video games are a medium of entertainment, you should play it because you want to. You read books because you want to. You watch TV and movies because you want to; there's no "incentive" to engage those entertainment mediums other than pleasure and enjoyment. The same can be applied to video games. While a visual/numerical ranking system would be nice, the majority of Halo players could care less. Just as long as they're getting quality matches and having fun, that's all that matters.
Also, you mentioned that you've stayed off Reach for over a week. Might the fact that you're an Inheritor have anything to do with Reach not having an "incentive" to you? I've taken you've beaten the campaign, reached max rank in matchmaking, and 100% all achievements, thus what is there to be an "incentive" to play?
I'd garner to say that if you 100% all achievements in Halo 3, beat the campaign on Legendary, and reached max rank (level 50/5-star General), there'd also be no "incentive" to play - because you've dominated every aspect of the game. The only reason to play Halo 3 would be because
you enjoy playing it. Thus, you don't play Reach not because there's no "incentive", it's because there's a lack of enjoyment.
But when it comes down to it, it's just a video game. Play if want, don't play if you don't. Simple as that.