A: -10, lag switching does nothing but screw over the user.
B: 2-3. They're not nearly as common as people like to think. A lot of people complain about getting killed by a modded controller as an excuse to cover their terribadness.
C: 2. KBM is only better in a couple of ways - sniping is one of them. In most other ways it's worse than controllers TBH.
D: 8. Very real problem. Boosting is where groups of people deliberately attempt to farm WP doing cheesemode things to get SP and ISK without actually participating in matches. It hurts the game because you have deadweight players and it siphons the ISK income off honest players. It's a bannable offence, though, and it's easily reportable. If you see someone mysteriously going 0/0 with 8000 WP and you never saw them in the combat zone, be suspicious.

Boosting however is a very real thing, and while not exactly common is pretty easy to identify. There'll be players on opposite teams with >6000wp (usually earned from some exploited mechanic) and usually no kills or deaths (until they drop ob's), the rest of the players in the game are often down at ~2000wp. Don't be too quick to call boosting though as a good logi can earn insane amounts of wp through triage, revives and team spawns - some if my highest wp games as a logi I've gone 0-5 with 6k wp,(certainly take a picture and report them if you're suspicious ccp will examine their in game actions to determine what they've been doing.)

i dont activley use it because of my headset setup. BUT i DO have high end programmable keyboard/mouse/nostro and yes... it does work AND is directly respocable for the "omg cal scout is OP it doesnt take damage" and so called "hitbox" problems that are so pupular. its also the reason why min assaults are so damn pupuylar right now, as high end players abuse the fact that its the highest strafe speed of the medium frames combined with KB/M super strafing to replicate teh sucess of the cal scout now that the cal scout no longer has insane wall hacks. people see this sucess and try to emulate it by also specing into the min assault without understanding WHY its powerful.