Each profile supports multisig and can update the smart contract code to fix bugs and add features.
When you create a new Surf profile, its address and seed phrase are automatically generated. Anyone can send you Evers knowing this address. If you want also to send Evers, you need to activate your profile first.
Please note that your profile balance should never hit zero. Otherwise, the profile will be frozen and you'll need to go through a complicated procedure to restore it.
The Surf profile smart contract has been formally verified. This means its work and reliability are not just tested, but proved mathematically.
The source code of the Surf profile is partly available on GitHub.