A: well, that depends on the sexual maturity ( or when all their sexual organs are fully developed)
Usually buy its 4-8 week they can already start breeding, but WAIT! It does not mean they are ready to be parents! Hamster mums whom are very young may not have the ability to take care of the babies!
Thus if you are considering to breed, make sure they are at least about 7-8 weeks before breeding them 
Additional precautions you can make after she has given birth is to cover one side of the cage to give her that extra privacy 
Yup! i also have the same problem though! But i have some solutions!
Glass bottles like this:
Firstly, the black/brownish stuff must be cleared, if not your hammy will drop fur!
2 Solutions :
1. Use a Q-tip/ Cotton Bud to clean out when you wash the bottles
2. Use a water guard: ( i use this, and so far its pretty good!)
Aristopet is pretty good too! It has vitamins which has helped countless of hairless hamsters, and a fab hutch cleaner for small pets!
Another brand which is cheap and good is ALEX! It has affordable ranges of awesome smelling mineral blocks and really quiet hamster running wheels too! Treats are always bought for my hammies too 
To end of this post :
TADA!
My super cute darling says HI! <3
