I just brewed up a patersbier a couple weeks ago, I used Northern Brewer's recipe:
I'm really looking forward to it.
I think it comes down what you want to get out of the beer. I'd say questions 1-2 are basically the same thing. If you want it to finish dry, you can definitely mash low (147-148), and even add sugar if you want. Just depends how dry you want it. I did a 90 minute mash at 147 for mine, per NB's suggestion. I can update in a few days to let you know how low it finishes. I think you'll find it'll finish below 1.010 without any sugar though. I can't give any advice on thickness or pH, I don't monitor pH and I think I just used the default mash thickness in Beersmith 2.
For question 3, do you want any hop flavor in there? I'm picturing a patersbier as a low gravity version of a BGS or a tripel, and in those styles you want some noble hop flavor. So I stuck with the NB recipe which has a little bit of saaz at 15 minutes.
I'd plan a 90 minute boil with all that pils.