Is it possible to define a template for a custom post type within a plugin independent of the active theme?

I’m writing a plugin to manage data about open-source projects. I developed an object model and have successfully created all custom post types and taxonomies, as well as implemented the correct capabilities/roles using the Members plugin. The appropriate users can create, modify, and delete their own posts, and administrators can approve them, as well as modify and delete anyone’s posts.

Where to securely store API keys and passwords in WordPress?

I’m looking to use a few APIs and many come with keys, secret keys and passwords required to work. Where in WordPress can you store that information? Assuming anyone can hack your DB is there anyway for WordPress to make saving that information more secure? Also, consider the ability to change these keys ever so often so I would need to update the keys on an options page.