If you already have the SCLogin module displaying on the page somewhere, you can add some code that will trigger it's popup. You could even put the SCLogin module on the page and use some CSS to hide the normal "Login / Register" buttons that would show, so that you can use it's popup. To do this, you just need to add the following link where the deal would be:
<a class="btn btn-primary" href="#login-modal" role="button" data-toggle="sc-modal">Log in for this link!</a>
If you want to put the SCLogin on the page, but hide it's normal login/register buttons, use the following CSS:
.sourcecoast.sclogin-modal-links.sclogin { display: none;}
Right now though, we don't have a way to set a custom redirection for each instance of the SCLogin module. You can only use "Same Page" or a specific menu item in the JFBConnect component 'New User Redirection' field. It sounds like "Same Page" would work for you in one of your options though.
The other option is to simply check if the user isn't logged in and, if not, add the {JFBCLogin} tag. That will show all the social login icons in the spot of the deal, but it won't show the Joomla login fields (not sure if you need those fields or not). With the {JFBCLogin} tag, you can select to use custom images just for that area as well, if you'd want them to appear differently.
I think this should give you some good suggestions to try out, but please let us know if you need more clarification.
-Melissa