Where are the logins stored

When users register with Theme My Login, where are their login details stored? Are the passwords encrypted? To what standard? How can I attach other information against their logins. Is it backed up?

I’m writing a website that will provide licence keys to users so I need to be able to attach other data to this information. An overview would be useful. How can I grab their email in other custom written PHP pages, so that I can use it to attach data to it in tables in MySQL and potentially email them?

I need to know this before I know if I can rely on this plugin. Many thanks.