She is pretty good sized I think she could handle small to medium rats.

That does look like pine shavings for the substrate. I am no expert on this but some say pine is bad for snakes because of the pine oils when you go to buy more if you want to stick with wood chips I would get aspen.

A lot of people here like to use news paper or paper towels on the bottom of their tanks when the snake makes a mess you can just replace it.