1. People don't usually say where they get their good proxies since it's not worth doing as the more botter use those proxies the higher chance of them getting flagged. If someone recommends you proxy seller most likely they dont even use it themselves
2. Not always, but often it works
3. You will need to change password since it will be locked if it will get quashed
4. Probably not. But somehow they sometimes decide not to unban you. E.g from experience, two exact same accounts, one gets unbanned, other doesnt. Both created/used the same way.
5. If you will use one account remember that at some point the fun will end. Either they randomly decide not to unban you 1st, 2nd or 3rd time or even they will state to you, look you have been hacked few times now if you will get hacked again and banned you are banned permanently