Managed to complete that lot, then got to stage 3. Then via Google I realised you could find the link to the final stage of questions without needing to answer the preceding stages:
Damn, Mike, wish I'd seen these earlier; my kind of puzzles.
"Sum" seems too straightforward; I can see how "Manifold Agreement" works, and the start of method for "Looter"...
Now, if I can just persuade my clients that I don't need to do any more work today!