It sounds like you're really trying to do whats best for your girls
Sorry I didn't get back to you sooner - I had to sleep and stuff
The bar spacing on the cage is far too big, ideally you want 1cm bar spacing or less but you can always get a cage with bigger bars and cover the bars with mesh from a hardware store
Hamsters would probably chew through most fleece and try to dig in it, for hammocks it can work if you watch to make sure its not chewed, but for substrate its probably not a good choice I'm afraid.