Tips for authoring Blueprints, anyone?

I created my first Launchpad project not too long ago: “The Schema Collective”. And I'd like to get started creating some Blueprints, but I'm not sure how to proceed.

Firstly, the project's goal is to provide a bunch of diagrams, XML schemas, and pre-generated code skeletons for a bunch of different standards (like VCARD, iCalendar, FOAF, DOAP, DocBook, etc.). So I could organize this by standard, or by something like “diagram for each standard”, “XML schema for each standard”, and so on.

Secondly, Launchpad describes Blueprints as being for a few sketchy sentences of an idea to a full-blown specification. However, this project only lives on Launchpad. So if I wanted, say, to write a more in-depth Blueprint, am I pretty much stuck having to upload something somewhere else? Could I write detailed documentation in the project itself, and have a Blueprint point to that documentation in the repository?

Any other general tips or best practices for authoring Blueprints?