no, you don't lose a lot of experience points....you do lose some cause you are going against the karma path you chose, but not a lot...and if you go against the path you chose so much that you losing rank, it sounds like you picked the wrong path....cause you shouldnt do that much...
no, you cant completely reverse your path...trust me, i've tried....once powers are locked, they are locked.....and even if they weren't, you wouldn't have shards to upgrade them...also, you cant go back and change the decisions you made in game to move the story along....
ok, I get that, but again, it sounds like you just want a guy with powers cause you don't want to commit to a path...but that's not how the game is meant to be played...