Yes, it is interesting that there is no minumum for the sequence diagram. For most people, that actually takes the most time.
As far as instructions go, it's pretty vague for the beta. I didn't see any actual objectives for part ** and part ***. People are arguing over UML 2.0 and UML 1.x, although I see a great indication that UML 2.0 isn't necessary.
I'm approaching it as though I were to present it to an architecture review board next week. I'm making my diagrams as informative and understandable as possible, without being overly complex and difficult to decipher. After all, that's what a good architecture design should look like. Who cares if it complies to the latest UML 2.0 spec if nobody can understand it.