No minimum. It’s just a self custody wallet. Send whatever as long as the token/network is supported.
Again, same way. Only thing you’ll need to remember is that when you do swaps, you’re going to be paying gas and network fees.
Crypto fees are always going to vary and aren’t written in stone. This is all determined on which network you’re using and what those network fees are like. I know as Brave had been using Ramp and all, there was a 1% fee. Not sure what they are doing on it now. But if you go to do a transaction, it will tell you all specific fees there. So you can play with things just to see cost without sending. It likely would be best for you to do that than to try to get people to provide exact numbers.
No hidden fees. Again though, there can be more fees depending on what you’re doing. If you’re just simply sending or receiving, then nothing. If you’re doing swaps or bridging, there may be a transaction fee. Brave will always reveal this ahead of time and you would need to approve it first.