I'd go with either a mac mini or imac, personally. You've already made the mac jump with the MBP, may as well go all the way. As to mac not being as "fine tunable" as windows, I'll just say I think mac's at least as tuneable, it just doesn't require as much work to keep stable.
Yes, I currently use my ipad for reading books borrowed from my library, using overdrive. I'd prefer to read it on my kindle, tho, generally. It's not the end of the world, just a preference.
The smallest mbp has a lower res display than the mba, if that matters to you. It also doesn't have the better graphics chip. But it does have thunderbolt. Thing's a giant behemoth tho, compared to the air.