[ejunge]

I keep mine locked on a daily basis. It doesn't hurt the watch. It just needs a battery replacement.

 

[ejunge]

Tightening the screws will usually compress the seal. Remember it doesn't need a lot of force to keep water out. If you got the case back on and it's tight, and you didn't cut your seal when you removed the case back ( by prying at it with a screwdriver) it should be fine.