First, Twitter doesn't allow the fetching of a user's email address, so that's something the user has to provide on a separate registration screen, like you posted. You can choose (in the JFBConnect configuration area) to automatically generate a username and/or password for the user. With those settings, you can basically make the form-based registration process very quick and just look like it's asking for the user's email address.. and not really 'starting from scratch' for a new account.
The benefits of Twitter are that you can get the user's name, profile picture, cover photo and other information imported into JomSocial (or other extensions). So, its still a few more steps than Facebook or Google, but still better than making the user do it all.
For Facebook, the reason it's not working is because the Bootstrap Javascript library isn't being loaded. In JFBConnect, enable the "Include jQuery" setting, and you should be good to go. That includes a compatibility version of jQuery and Bootstrap.
I hope that helps!
Alex