"iterative process of gradual reduction" means making multiple passes through all the footage, getting more and more selective each time.

Re: music - Check out musicbed.com Great music you can buy the rights to immediately. Great staff, too.

Re: the can of worms - When I moved to FCPX 2014 there were a lot of reasons that don't apply anymore. Right now the thing keeping me here is that on a mac FCPX is proven significantly faster than PP. I've got a cMP with GTX 980ti which crushes almost anything I throw at it, whereas PP still has very limited use of GPU acceleration. Ironically, I still use (and love) AE because Motion sucks donkey balls.
As far as integration with the whole suite, you obviously can't beat sticking within the Adobe world.
All in all, they are both very capable NLE's and I'd probably go with whatever you're more familiar with, which is Adobe. Can't hurt to get a free trial of FCPX, though, if you're interested.

Personally, I find the music that I want first, which gives me a pretty clear vision of how I want to edit (music inspires me like nothing else), and that makes it easier to start organizing because I'm doing it with an end vision in mind. So, do whatever you need to do to get decently clear on the video(s) you want to end up with before you start organizing and then you'll know the kinds of categories you need and the shots you want. It's been a while since I've used PP but I tag footage with colors (yellow=useable, green=go, blue=beautiful, purple=phuck yes) which carry over into FCPX even when I've placed clips in other folders. So if there's a way to do that in PP maybe you'll find that useful.
Another easy thing to get started is just to go through your footage looking for clips you can trash right away (don't actually trash them but mark them as rejected or move them to a separate folder.) Makes everything else easier later on and seem less daunting.
Hope that's useful.

I've heard great things about the Came Single. And it's cheaper than the Came mini 3. For a camera like the 6300 or even an A7S2 it's plenty.

Not every NFS reader is as equally proficient as you, Professor Brewer.

What kind of style? There's Osiris, Impulz, Rocket Rooster, Debuts... The list goes on.