How can I make an SBT build for multi-projects and multi-platforms?

Question

I'm starting on a medium project with many independent components that can run either on Android or the JVM and I'm wondering how to break it into SBT projects so that the dependencies behave nicely. Here's what I've got so far:

core/ for platform agnostic core code, must not break on either platform, this includes interfaces for component launchers

android-core/ for implementations of the core interfaces that depend on android libraries (note, this project depends on sbt-android)

jvm-core/ for implementations of the core interfaces that depend on libraries that don't play well with or depend on android

So far so good, but now it's time to consume the core projects in the individual components. My requirements are:

• Each component should compile to a separate Android app (perhaps sharing an aar library?), and the apps can be individually installed (still via sbt, a la the android:install task)
• There is a wrapper build so that all project builds can be done from the same place.
• It is so easily extensible that fresh grad students can correctly add components (bonus points if adding a component needs no change whatsoever to the build).
• If a component depends on a platform specific library it does not prevent other components from being compiled agnostically.

Some of the questions I have are:

• Should each component have an sbt project? (I'm inclined to think so so that students could add dependencies on libraries that don't run on both platforms, but I'm open to being wrong)
• If so, will each component's project require an sbt build?
• If so, how can I bootstrap the component builds to require minimum skill from the component author?
• Later I'm going to be adding code generation to generate message classes from descriptions (think protobuf/thrift), that will want to run as a first pass before the components get compiled, I'm assuming this can be done, but do you have a link that explains how?
• If two components each compile against the messages of each other will that create impossible circular dependencies?

Basically I'm looking for wisdom and experience, the nitty gritty code I'm sure I can hack my way through once I know what terms to search the docs to understand and roughly how the whole thing wants to hang together. Thanks for your help!