My Inspiron with two battery packs gives me approximately 6 hours of power. And the screen is easier on my eyes than desktop monitors. I like this thing.
For storing images an external hard drive is the ticket, pics will eat up space very quickly.
Nothing keeps you dry in nasty weather. Precip vs Goretex, waterproofness is irrelevant. Both will keep you less wet than a non 'waterproof' fabric. Gtex will breathe a bit better, but I doubt you'll notice it in the field. Choose a jacket for its cut and features.
Yes.
Given that Mr. D00kiebird is a rabid environmentalist, I'm surprised that he isn't more concerned about the enviromental impact of his chosen form of recreation.