1) bugs will kill some small ships easily with 1 ram if they have taken some damage (which is when you should ram them), but they do very little damage against non combat ships (as these have no weapons to detonate) like constructors, so ramming a construction ship is not a possible tactic anymore, you are restricted to blowing it up the old fashioned way.
2) a bug will never survive a successful ram. if the ram is successful (and damage is dealt) then there is 0 chance of the bug not dying. there is a chance of a failed ram, where the collision will do no damage, but the bug will immediately lose all crew, and become derelict. So a failed ram gives the enemy a free bug
3) all i know is bugs deal very little damage to non combat ships and to stations, thus ramming these things is pointless. the more a bug ranks up the more damage it deals and the less chance of a failed ram. veteran bugs can take out large stuff like cruisers in 1 successful hit. but if u have a veteran bug, its hard to blow it up instead of keeping it. ALL successful rams disable engines and push the enemy away for a short while. this can be super useful against borg, a cheap bug can be used to stop a sphere running away and regenerating. thus as a borg player, target the low defence bugs first (which the computer will do for you).
4) i just answered this in the last section, i typed it before i read your 4th point. as i said, bugs do great against regen spheres that try to run. ram from the opposite side of the sphere, so it is pushed back towards your waiting bomber spam. it only disables engines by default i believe. and it lasts a short while, maybe about 10 seconds.
