I don't think there is a difference. I use social connect plugin on my websites and everything's fine.
Yes it can, depending on what infos you want to collect you can ask for required perms in the application and if user allows, you can store that info.
So i can request for Facebook ID, Name, E-mail. Then create a database that stores that info, so if they log back in the database base will search for facebook id, name, e-mail of who ever is connecting and then reload stuff like pictures they have uploaded msgs and so forth.
Sorry if it sounds noobish i know some Sql,php ect but im no master.
Trying to get as much info as i can before i even atempt to start on this project.
yes.
If you want to grab their albums etc you will need your app to ask for required permissions.