I figured out the DTP issue, I was used to using the database-specific enablements, with 1.7.0-up it seems to be wrapped underneath a single plugin (at least that is what it appears) instead of individual plugins, but doesn't seem to be working like previous setups -- see below.
If you are using the JPA project, hibernate tools project, etc, there is the, under Eclipse->preferences, the Data Management->Connectivity section that lists all jdbc.jar's loaded into the system and the jdbc-url templates ready to go. Once the Data Management/connectivity is setup with those jdbc.jar/templates, all the other tools can now use those references. Using your words --
"expose a driver jar in a plug-in and create a driver template that automatically picks up the jar in the plug-in and pre-populates"
What I am looking for, whether with DTP or some other plugin, is a way to get all those jdbc.jar's setup, templates setup, exposed through Data Management->Connectivity through some type of plugin approach instead of always browsing through the filesystem to setup the jars.