Apple Care for Mac & Time Capsule

[Moccasin]

I'm considering buying a Mac Mini and recall that if you buy a Time Capsule too, you can cover both with the same Apple Care.

How does this work? Do both have to be bought in the same transaction? Do both have to be bought from Apple? Do you still have 12 months to buy the Apple Care?

I already have a late 2010 MBA and so would want to back both machines up. Is Time Capsule even the right solution or should I go for a USB/Thunderbolt drive attached to the Mac Mini (or indeed both that and the TC).

I have a ReadyNAS Duo with a single HDD but find this noisy and rather annoying. I'd rather invest in a better backup solution than buy another HDD for the empty bay.

My only doubt is whether to wait for the next Gen hardware in the hope that this has the new wifi standard (unlikely as that may be).

All advice welcome. Am open to different solutions, though not one involving a NAS.