hi,
1,2,3 are already possible.
4 will be possible in the next version : mass, center of mass offset and inertia scale will be editable during runtime.
for 5 i assume you need an auto-gearbox without auto-reverse, i will add an option to disable auto-reverse for the next version.
about the next release, we are in the testing phase right now, it will be available in a week or two.