The image ability for JFBConnect was added almost specifically for problems when used in a modal (as well as flexible customization for everyone). Glad that worked for you.
The LinkedIn button has some styles already specified for it in /jlinked/components/com_jlinked/assets/jlinked.css You can override those in your template or change them in that file (would recommend your template so they styles aren't overridden when you upgrade). If you need to set your own styles on the button, we can help with that too, but that requires some code changes to JLinked itself.
As for Tooltips, what do you mean? You can override the SCLogin module's login template and add text/tooltips next to the buttons. Alternatively, we can help you modify (as above) JLinked or JFBConnect to change the button output itself.
Finally, for LinkedIn, unfortunately, there isn't currently a way to do that in a popup. It's really annoying since it looks like a popup, but that's been a persistent complaint to LinkedIn's API devs. We're looking into alternative ways to force it into a popup, but haven't had any luck so far.
Hope that helps explain,
Alex
SCLogin in modal with FB and Linkedin
