I have read a lot about PHP login security recently, but many questions on Stack Overflow regarding security are outdated.

I understand bcrypt is one of the best ways of hashing passwords today. However, for my site, I believe sha512 will do very well, at least to begin with. (I mean bcrypt is for bigger sites, sites that require high security, right?)

I´m also wonder about salting. Is it necessary for every password to have its own unique salt? Should I have one field for the salt and one for the password in my database table? What would be a decent salt today? Should I join the username together with the password and add a random word/letter/special character combination to it?

Thanks for your help!