My gut feeling on producing supplements, adventures, etc, for BRP is that they should take into account some of the optional rules for usability, but in general they should stick to the core rules for brevity - I still remember with a bit of a shiver the pages and pages of creature statistics all with marginally different hit location stats... oooohhh...
Pity the poor trees!
So, for example: in an adventure, opponent stats would be presented in line without hit location / strike rank / etc stats. However, if a new creature was being presented (ie a "new creature description" rather than a simple stat block for an inline monster), then hit location should be addressed. Note that this could simply say something like "Hit locations are figured as for a standard quadruped"; you'd only need to point out the actual hit locations if the body form of the creature was not included in the BRP rules (9 legged 2-headed chaos monster, anyone?) Strike ranks aren't so crucial - GMs can always derive these from the existing rules.
Benchmarking starts to get a bit more tricky when you get to magic. Which system to you use? Again, my gut feeling is that magic systems for fantasy supplements will default to "setting specific" (so my own Chronicles of Future Earth campaign uses a modified MagicWorld system, and scenarios for it therefore assume that system), whereas "generic" fantasy adventures or critter sourcebooks will probably settle on a consensus, which IMHO may well end up being the MagicWorld-derived system due to its similarity to "other magic systems" out there.
Fundamentally, though, regarding the Core Powers systems, etc, I see nothing wrong with a brief paragraph at the start of any supplement or adventure just stating the assumed rules conventions - Traveller used to do something pretty similar in the early days, when Basic Traveller, Mercenary, High Guard, and Striker all coexisted. Referees will usually chop and change what they don't like anyway!
Sarah