1. Give credit where credit is due. Using kills to deaths ratio as a measure of balance seems very haphazard and inaccurate. This doesn't take into account the fact that you are awarded kills standing in the vicinity of other players fighting or for players you perhaps clipped with your AOE but did not directly attack/were focusing on. Let's face it, you might have a bunch of kills on the scoreboard, but the majority of them came from fighting next to that Mara/Sent. You can rack up a whole bunch of kills by dotting up people that another player does all the heavy hitting on. This also doesn't take into account that the kills and deaths counter in game seems wildly inaccurate at times. I can attest, as I'm sure many others can as well, that I have died way way more times than the scoreboard shows.
No idea about 2 but you are missing the point by a huge margin here, because you are only thinking about 1 player, rather than 1 million players (Or however few people play these days).
Yes person x might get a lot of kills in a warzone from 'leaching' other people's kills, but over the whole population of the game that kind of thing evens itself out, because person x might be a different class tomorrow. So when looked from the top level this is a very good measure to see how well people are doing. Actual class balance where each class puts out the same DPS while maintaining different playstyles and levels of burst is very hard to get right (No MMO has managed it yet, at least PvP wise), but the whole point of that balance is to make each class give the same reward for the same effort. So as long as the reward is balanced that is a very good place to start.
Any class you feel is underpowered may indeed be so, but aside from you not feeling like you are powerful it doesn't seem to be actually preventing you from getting the same stuff that the more powerful classes are getting, at the same rate.
You are right that player feedback is important, but you need to actually put some serious thought and facts into your feedback if you want it to be taken into account, because facts like kill/death/reward ratio's are hard to argue with, and most people would prefer to know they will get an equal reward on all characters, above actual balance, only those who play competatively (Usually a small %) even notice anything other than a major balance issue.