Alright /out/, I usually hate gear-threads too, but I need your love.

Wife and I are gonna buy some kayaks. We've rented and borrowed plenty, but we don't know the ins-and-outs of what we're doing. So here's what I would like to know about, and am hoping that you can oblige with:

1) If money isn't an issue, what am I looking for?
2) If money is an issue, what am I looking for?
3) What's the right kind of paddle for wanting to also go up the river?
4) What's the cost-threshold where it goes from “you're paying more for not much better” to “you're paying less for just as good?”
5) What other gear do I not-yet know that I need, besides gloves? (fuck that place next to my thumbs hurts, after this weekend's 30km trip)
6) Do I need a kayak rack, or is my ski-rack cool if I just buy straps that grip it good-enough?

I'm 6'4” and 200lbs, and wife is 5'5” and 100lbs. I didn't think that'd matter, because the kayaks we rent always have multiple grooves for different heights. But I'm starting to think that the reason that those grooves exist is because it actually matters a lot.

Anyhow... I know dick about kayaks. And I'd appreciate whatever insight you've got to offer.