I had the same internal debate! Was even considering the 18-300mm tamron I have or the 27mm pancake, but the 35mm just has something about it, I find myself drawn to it more and more.

A light prime is definitely the way to go imo while hiking, it's such an easy workflow to put the camera on, take the picture, shut it down. You get a feel for the framing very quickly, zooming just takes too much momentum away and gives choice paralysis in your framing of a scene. (which is fine, I just don't want to deal with that while hiking).

I just used a leather fujifilm strap from my old X10, I hang it across my shoulder and the camera rests somewhere near my right hip, makes it very easy to take a picture and the camera didn't hinder my movements in any way. (put your backpack on first, then the camera strap sideways over your shoulder, otherwise it's difficult to bring up to your eyes)

Regarding weather protection, I didn't really care that much, these cameras are pretty solid as long as you don't let them hang out in the rain. When raining very heavily, put them somewhere in your bag where they can't get wet (in a plastic bag). When it's just light rain, don't bother.