Pathfinder is way easier to use than 3.5, practically speaking - by this, I mean that resources for Pathfinder are just easier to get than resources for 3.5, even before you discuss the systems themselves.
And by resources for pathfinder, I mean
http://www.d20pfsrd.com/
Re: setting, the TNP fantasy setting just isn't very fleshed out. If you're up for something along the lines of a custom world, I could act as a Loremaster for the campaign - it's been a long time since I've played Pathfinder, and RL is more of a concern for me, but I could definitely help you run broader lore aspects if you needed the help.
I've never really been a fan of low-magic D&D - I'm of the opinion that D&D is built for high fantasy, and hence low-magic D&D tends towards ruining suspension of disbelief. Not that I don't like low magic worlds, I just don't think that many D&D classes work for it, and it kills a lot of the native flavour Pathfinder has.
For rolls, GM rolls would work best, I think - player declares their roll, "2d20 + 8", GM gives them their result "16 + 8 (+8) = 32".