Yep, 10 total. Only 4 have been identified so far. Although I guess you could probably include the tsuchikage's dust bloodline... which would be... earth + wind?
Oh yeah, and the 3rd kazekage's black sand bloodline, which could be earth + lightning.
The rasengan as everyone else has been using it was an incomplete jutsu; the rasenshuriken beng the complete form. It really was meant to be an aoe projectile like what the demons use.as for the blast punch being over powered - it's just how the rasengan should work. a one hit kill punch, perfect for slugging it out. it's just that Naruto never gets to show off his moves in a fight where he has the advantage.