Please tell me the thermometers and hygrometer are digital.

Is there any specific reason you are choosing to feed in a separate container? I started out feeding in a separate container, but found that my bp did not eat well. Now I feed all 6 in their enclosures with great success. (not that you can't have success with the feeding box, but it's just not as common)

Yes, you can switch from aspen to another substrate, but you may have to contend with some stress. I switched to aspen to newspaper with no problems, but all snakes are individuals and can react differently.