For you question 3, like one of the posts said as your landings get lighter then so does the replacements of the dampers. Do what i do heck buy some new ones keep them on stock. Or a little IC-2000 Cyanoacrylate Like C.A. but black for its rubber adhesive, clean up the broken dampers and glue them back , yeah its solid now , no play but it does work for the time while your going through a few .

for you ball link for the controll arm in the tail . That is weak after a few flights , i took some regual medium C.A. Drop it in Screw it in nice and solid , not a strip out. next day its not moving. make shure you use a ball link sizing tool for the ball link so theres no friction back there this will cause it to wiggle out as well . hope this helps.
As for the gears, mine has never had the problem, and i have three of these. Sounds like a flaw call Horizzon have some one that flys em look it over for you as well if you can.

After you run a gallon of nitro though the heli . Set down go though the whole thing, not missing one nut , screw , servo .