Robbie - I'm just a dopey old wireman and not a contractor, but I'm also involved with project management, contacts and estimating. From my perspective I can answer all your questions with one single answer, and that is I just wouldn't do the inspections at all.
Look at it this way, you have a resi customer or (worse) an insurance company who are trying to find someone who will make a determination that the alu wiring is safe. You really don't need to see it - it's not. What I mean is, even if it's OK today, it will deteriorate tomorrow, and unless it's regularly maintained (which you cannot control), it won't stay OK.
The insurance company really worries me - they're likely looking for more than mere assurances, you might be bitting off more legal liability than you know.
'fraid I'd run,
There are 10 types of people. Those who know binary, and those who don't.