Hi guys , i want to get a go pro but idk nothing about then , model and everything...

Are they all waterproof ? ( do you need a case )
What ill do with it
-mostly fishing
-hiking
- more to come ahah

Can i use it at home like a webcam ?
Will it be better than my logitech brio ?

Which one would you buy ?

Hero 7 ? Hero 8 ? Or 9 ?

Also which accessory is a must ?