Just so that you know, I dont think this is important enough yet to fix right now, but it should get fixed in the next official release, whenever that is.
The water thing is probablly more important than the grav--particularly since more and more maps have water. The projectiles are not that much of a problem, but if someone made a moon base with moon gravity, you'ld expect the projectiles to go farther. The way it currently is, at moon grav an adv goon could pounce six times as far(I think), but its sniping attack would still have exactly the same range.
Just an idea for a solution, would it be possible to make the projectiles use the same physics as players? That would probably be the simplest thing to do.