Make sure when you download the installation files from SourceCoast that you unzip the original zip file before trying to install. You should be installing a file that looks like com_jfbconnect_j1.7-2.5_v4.2.0.zip. If that file is giving you the "No installation XML has been found", that would be very strange. If so though, let us know.
Regarding the Send button, we've heard another report of the send button being 'missing'. So far, it looks to be a Facebook bug, not JFBConnect. Can you try going to the page below and putting your URL into it?
developers.facebook.com/docs/reference/plugins/like/
If the Send button doesn't show there, that's an indication that it's on Facebook's end. Let us know, and we can file a bug report with them.
Thanks,
Alex