If you use ISBoxer then the need for identical classes isn't all that important. A DPS and a healer is fun. Something like an Ele Shaman and a Disc Priest works well. That way you can get better efficiency on loot drops.

I did dungeons from 10-80 on my last 5-man team. It was quick and painless. With only two team-members you'll probably want to quest. That goes really fast with RaF.

Know that RaF is currently turned off, although I think it will be re-enabled real soon now. When it comes back it will be 1-85, instead of 1-80.

Yes, you can recruit your own email battle.net account. That's a really good idea for many reasons.