Tuner cards

Since this thing is going to be my PVR, I need to have at least two tuners. Maybe three, just to one up my R*gers PVR.

Things to find out:

1. Should I get a single card with multiple tuners?
2. What kind of signal does an OTA antenna bring in? Ie. What do I need to be decoding in the tuner?
3. Is there different output resolutions involved? Do they all output 1080i?
4. Are some cards more easily supported by Mythbuntu?
5. Are some tuners more sensitive than others? Are amps required?
6. What about sound outputs? I want 5.1 at least.
7. What else don't I know?

To be continued...