I know it's difficult if you buy a cage and end up with a bar chewer. I think most people on here have found that bar chewing in a 100cm cage doesn't happen. There has been the odd case of a chewer who has chewed through a plastic base though! I think bar chewing is basically cage size and stress. Stress caused by too much cleaning out or unsuitable set up - ie not enough substrate, nowhere to hide, not enough enrichment, not being able to access things etc.
There are some hamsters where it has become a habit though, but if you get a baby/young hamster that is unlikely.
As regards depth of bedding - varying views. I know the Germans say 30cm deep bedding for burrowing! Some hamsters will dig and burrow and some won't. My experience is they don't tend to bother digging burrows when they have a good house and are happy with 6" of substrate. Robos nearly always dig tunnels and burrows. Our last Syrian was a digger but then used to hide away too much so I actually reduced his substrate and gave him a big house. Our previous syrian ignored substrate however deep it was and didn't dig at all - except once when he only had a small house and then he dug a burrow - which got stinky and messy - and he didn't look too happy. Gave him a big house, he moved in and didn't bother to dig much again
Their most important things are somewhere dark to build a nice big cosy nest and the ability to bury hoards under their nest. Aside from that it is space, variety, places to go, things to do. And food!
I have a labyrinth house in my cages and the hamsters always move in! Because it's dark inside as has rooms and light doesn't go round corners. Before that I just had a guinea pig house with a bendy bridge tunnel over the door - same effect.