1)If you look at the games, you can use force choke as a light side jedi and LS powers as DS jedi.
2)During this period, Luke had very little formal training, he studied with yoda for a few days then left to help his friends. The rest of it, he more or less learned by experience...
3)Luke uses a lot of different force powers during that encounter, it may have been just a little arrogance on his part. Did he really have to jump off the plank just to hop back up with the force? NO, he could've turned around and have r2 send him his saber. Luke was "not a jedi yet"