Juliet,
Sounds like a normal visit, although you always hope for more information. The decision for me was based on a combination of facts and educated speculation mixed in with some good old fashioned fear of the unknown.
You are getting a good start here - at least you will have a better shot than I did at being prepared.
The "no evidence" of perinural invasion would come from the biopsy report - mine mentioned it where it was found. The PIN - mine was "high grade". I'm not sure that it is a factor in chosing between surgery and radiation, it likely is for chosing AS, but then my uro brushed it off as common. I wound up doing DaVinci. I didn't like the percentages on radiation either, but now I've got the surgery side effects. Time will tell if I made a good choice.
I didn't see that you mentioned getting a copy of the biopsy report. If you did not, call and get one.
Not sure that I can offer anything else at this point besides my advice to proceed calmly, but with determination, and my best wishes.