Hi, I'm a relatively new PvPer like you, but thanks to the people here I managed to figure a few things out:
3 & 4: Medals are awarded for very specific things, like amount of damage dealt, amount of healing done, guarding a node, etc. It is possible to do these things without actually helping your team win the match. For example: a sorc/sage can use consumption/noble sacrifice to deal themselves HP damage, then hide off in a corner the whole match and earn medals healing themselves.
Bioware has coded medals for a number of actions that can reasonably HELP win a match, but it is a matter of how and when you do these actions that actually determine whether you actually do contribute to winning.
So to sum up, it's possible to earn lots of medals but not contribute to the match very much or at all. On the flip side, it is possible to not earn very many medals at all but be a big contributor to the win. An example of this: it was ACW, and it was close. We had snow, but the enemy swarmed it. We would run in to disrupt cap, die right away and respawn to snow to do it all over again. Not the best strategy, but we stopped the cap until the last 3 seconds of the match and won, but we were all at the bottom of the scoreboard.