1 Is there a way I can transfer items from one backpack to another more quickly?

2 Can I change the color of the sleeping bag on an already made backpack?

1. Not possible, you can maybe use hopper and place one backpack above and one backpack under, it will transfer all items from storage space in backpack, upgrades and tools wont be transferred
2. Yes you can - https://github.com/Tiviacz1337/Travelers-Backpack/wiki/Changing-sleeping-bag