1.) When I run my tournaments, I've got my share of players who are new and don't fully understand the game. (Heck, I don't fully understand the game, but I digress). I try to make it a level of play that matches the higher tournaments, so when my players attend the big stuff, they know the drill. If they play an enhancement, (or other card) it sticks. (Play in this sense means "hit the table"). However....
2.) Players are absolutely free to ask their opponent/another experienced player/me (as the judge) about a card before they play. In this case, I don't talk strategy, but do explain both the ability of the cards and any extraneous information (for instance, Martyr can't target Abithar)