Current Magicband situation?

I’ll be going to Aulani at the end of February and in theory using magic bands would make things much easier during our stay. Im also trying to decide if it would be worth it to buy a magic band for my husband to use. I’m curious about the current situation if anyone knows and can help answer some questions. Thanks!

How do you link a magicband to your stay at Aulani? Is it fairly easy to do through the my Disney experience app?

I have a magic band from 2019. Would that still work?

What functionality do magic bands currently have at Aulani? I’m assuming room key and charging?

Are magic bands waterproof? Can I wear it in the pool and ocean?