PDDP question (shipping to USA)

Hi everyone I hope these are stupid questions but I just wanted to know:

1. Do I have to use the PDDP system to calculate taxes duties etc. if im just sending a gift? Or will I just be able to send an item normally?

2. If im sending items to someone and they’ve paid for it to me but im not a business do I have to do it through PDDP? These are just like second hand items that don’t cost much

3. Also for the PDDP registration they need you to fill in your business info but I’m not a business and are probably only going to be sending gifts/occasional sales here and there like second hand items. So im confused what im supposed to do here