the aspen litter in infinity cheaper then the carefresh here. And yes, the aspen is safe. Just make sure your never get ceder by accident. While aspen is fine, ceder has oils that are harmful.
Your right in that you don't want the chin walking on the cage bars itself. They can get there feet caught in them and break a leg. And that sometimes is an injury they cant recover from. So you definitely want a tray or something to cover that up.
The only other thing worth noting is the hammock. Most chins will eventually chew on that kind and tear it up or eat it, which can cause problems. You might want to look into fleece hammocks. There are several ppl around here that can make them.
Congrats with the new chin!