I've read this SO post which led me to this FB policy page, which seemed to include some pertinent information, but I'd like more of a community response, maybe some experienced FB API people who know the limits.

My question is if I can use Facebook's Login api to, essentially, create a new user on my website. I really would just like to allow users to easily "transfer" some data from FB in order to more easily create a new account on my site.

I realize, first and foremost, that I would obviously announce to the user that by click "submit" in the form, that they are creating a separate account on my site.

Pertinent blocks on the policy page state:

You may cache data you receive through use of the Facebook API in order to improve your application’s user experience, but you should try to keep the data up to date. This permission does not give you any rights to such data.

Which doesn't look good for me, but also this:

If you stop using Platform or we disable your application, you must delete all data you have received through use of the Facebook API unless: (a) it is basic account information; or (b) you have received explicit consent from the user to retain their data.

Which, in my case, I would be satisfying part B. I would be asking the user's permission to retain the data, as I am simply using Facebook as a conveience to the user when creating an account.

I also realize that Facebook has a registration API, but this would require a Facebook styled login form, along with my own sites login form, and I'd rather one interface, as this makes it easier for me on the front and back end.

Any thoughts?