Connect Views and a second database
I havent done this but I have seen code to make Views in D7 work with remote database tables. If you can get Views to see those tables and fields -- a bit more work should be able to allow you to filter/search through this stuff from Views:

Fields with Multiple Entries in Views w/ External Data Source

It looks like you just have to give drupal a database key for your remote database connection defined in settings.php per field description. The rest looks like a typical implementation of hook_views_data().