1) Like that in live, unlikely to change, this is the cost of being terran and being able to solo better than just about anyone else, long as you can go faster than them.
2)Not that bad a plan, at least worth considering
2a) Meh, from a balance perspective, trading was kind of designed to be a long thing. Missions or whatever we get to cover for them should help on this front. Selling stuff you find on dead corpse isn't REALLY trading, its just the games way of giving you money, not at leveling up.
3) While nice in theory, takes a lot of work, and is probably unlikely to happen anytime soon. Priorities
4) Low levels are fine, we go through them almost too fast as it is, though that's just an opinion.