To answer your first question, you could co-locate the Extension Pack with a Site Server - under certain conditions. Please reference our deployment guide, which has a wealth of information on planning your Patch Manager deployment.
The trial is fully functional - the only limitation is that the 3rd Party content is not currently the entire set of packages available in the full product - but we do give you several packages to show how the process works and test it out.
Correct - once you are licensed for the full product, a key can unlock the trial to the full version.
So just to confirm once I enter my product license key, its becomes a fully functional(including 3rd party updates) product?