More important is seeing for yourself as to whether the work was done OK (if you can), if the rafters are adequately supported as are the window heads then jobs a good'un. When was the work done? Got any photos? Speak to the owner.
Bear in mind the usual surveyors get out clauses and hiding...
Ask him why. Fibreglass is OK provided he knows what he's doing. EPDM is far more forgiving. There's a mahoosive thread on here somewhere with people complaining about their roofs expanding (and making cracking noises) in the heat, I recall it's generally to do with enough fixings of the board...
You won't know what they'll want until you ask, they might tell you over the phone but then no guarantee you'll get the same inspector when you put the Notice it. In modern houses they typically carry on the strip under the garage door anyway as it makes building the footings easier.
Silicone everywhere for me, it won't look out of place provided the colour is right and it's done neatly. I would question why wouldn't you seal between the floor and the walls/pan on a floor that's likely to get wet.
But you've got a loft leg every 600mm in every direction - correct?
TBH if I was forced to use loft legs I would probably have a bit of timber around the perimeter of the boarded space but that's because I think having the boards unsupported around the edges is a bit crap. But then I would...