[Toadling]

First of all, I'd save all those tech notes outside of OmniFocus since they're really reference material that is not specific to any one project. Besides, at some point you might want to search/browse/archive that material irrespective of your projects, so an independent system for that kind of stuff is a good idea.

With my reference material in a common, easily-accessible place, I'd link particular items to my OmniFocus projects by simply dragging the file (or link to a database item) to any associated project. If the attachment is a file or folder (instead of a database item), it can be easily previewed with Quick Look from within OmniFocus.

The nice thing about this approach is that the reference material can be updated as time goes on and all your projects will still be linked to the most current data.

If the action or project with linked reference material is something I'll be using over and over in new projects, I create a template (with the reference material still linked inside) and mark it as dropped in the OmniFocus sidebar so it doesn't interfere with my active items. Then, when I need to create a new instance of the special project, I just Option-drag my template to wherever I want the copy to reside, mark it as active, and fill in any details particular to that instance.

-Dennis