Socket Identify

I have a few questions about the Socket Identify:

1. What format is the ID value? If you store the user’s socket ID in a database, what format is the best field to use?
2. Do I understand correctly, if several Socket components are installed on the client side, then each socket will have its own ID?
3. The probability that the socket IDs of different users will match is excluded?
4. The socket ID of the same user changes from session to session, or will it always be the same?