Hi,
I think I can answer your questions:
1. Are you using the latest beta? If so, on the settings screen you can indicate which links you want in the mashup balloon (directions from, directions to, and zoom).
2. If you use ‘marker_link=”true”‘ in mashups (it should be the default) the POI balloon should display the post title, post thumbnail and post excerpt instead of whatever is saved in the POI itself.
3. See #2, it should show the thumbnail as well (in mashups)