Yes, we would recommend using SCLogin to connect the Facebook users. It sounds like you've already gone through the configuration process to setup Facebook already. Therefore, if there are no social login buttons showing, please verify that the SCLogin > Social Button Settings > 'Show Social Login Button(s)' option is set to Show. Also, I'd suggest keeping the 'Providers' section blank or set to "facebook". Please verify these options and let us know if you continue to have issues.
Yes, you're correct that as soon as you map the users, then you can disable the login module and then follow the
channel setup guides
to set up the channels and the SCSocialStream module to pull in the streams.
-Melissa