Since self leveling may be a while off, what I do is get to 0.0 on the Z axis and then target a distant nav, press the space bar to point that direction. Now that you are pointing level, use the left/right arrow keys on your keyboard to aim for the freewarp and no more ceiling/basement bouncefest ^_^
As to the weapons firing at one target, then changing target and having to restart your weapons on the new target, it is a safety feature. Previously you would change target, purposefully or accidentally, continue blasting away, create a new enemy and then gain aggro from more than you may want to have pounding on you at one time.
Personally I prefer it as it is now ;)