1. dont lift it, get a hand trolley from bunnings ) I think they have handles built into the base tho... well my 8" does.
2. er... can remember numbers exactly but the 12er will let in more light than the 10... noticably.
3. get yourself a map of the sky, learn some constellations and jacks your aunty. there are mods you can do to make the dob move smoother too
4. NO! to me its all about the hunt!
star hopping with the aid of a chart is the way to go (for me).
5. if you lay the seats down it should... measure first tho