[Jeir]

Unless you have a glass cage, there is always the risk of a hamster chewing its way out. There have been hamsters that chewed their way out of the plastic bottom of some wired cages, for instance.

Unfortunately, you can't predict whether a hamster will be one that chews a lot. Most will be happy chewing on cardboard, or treats in the cage (walnuts in the shell, whimzees, and various toys that pet stores sell that are made of plant matter), but if the cage isn't big enough, or there isn't enough enrichment, they may decide that chewing on the cage itself is preferred. Males also tend to be calmer than females, so you might want to keep that in mind.

As for the wooden cage, you can spray the wooden parts with something like Plastikote to help waterproof it, but generally, if you've put a sandpit in the cage, they will start using that to go potty. Hamsters are very clean animals, after all. Having deep enough substrate should also help protect the base of the cage while the hamster is potty training.