ATF change problems

[r129 300sl]

Hi

Changed the ATF today. M103 engine and 4 speed gearbox (1990). Encountered a number of problems:

1) 5mm hex drain bolt would not undo. The hex stripped! Therfore had to drain fluid by taking pan off, not too much of a big deal since had to change filter anyway. Anyone have any tips on getting the drain pug out for next time?

2) Could not drain torque converter. After stripping the drain pug hex was not too keen to apply too much torque. How much fluid did I leave in the torque converter and will it make much of a difference?

3) Fluid level now a bit high. What effect will this have on gearbox? Should I remove some by sucking it from the dipstick?

Thanks in advance

Regards