1. Is she going to get fat on Orijen?
No - like people, dogs get fat from eating more than they need. When I fed kibble, I always free-fed - and I never had an overweight animal. Maybe that was luck - but I never did anything but free feed w/ kibble. In fact, if you consider high protein vs. high carb - dogs would get "fat" on carb faster than they would on protein.
2. Is she going to consume a ton of water and then have to pee every other minute if she eats Orijen?
Never experienced this - though I recall one member saying this, anecdotally. Several others feed 42% protein and haven't shared the same experience. I think if it was really common - we'd see a LOT of posts about it.
3. If I can't or don't order that eicosaderm what is it's alternative from say my vet (if he even has) or the local human health food store?
Vets, actually, often carry Eicosaderm - at probably double the price

. Otherwise - you'd probably want to get "Grizzly Oil" or any fish oil supplement from the pet store - and then supplement w/ vit E.
4. Does Eicosaderm (or it's alternative) help skin AND coat?
Yep! EFAs are very good for skin/coat and overall health.
5. If she is just a pup.....what do you think it is that is causing the itching? Where do I start? She is a little flaky where she itches.
It's funny bc sometimes, I thing puppies just get itchy as they grow. Marcel was itchy when I made him wear a collar (for the bell). It's really hard to say - if your vet has done a very, very thorough check (mites, mange, fleas etc) - and has ruled out everything - then I'd shoot for getting her on a premium diet, on fish oil - and seeing what happens.
What was she on for food at the breeders? Can't recall what you said - but if she was on anything funky - the skin is an elimination organ, so she may be getting rid of some gunk too...
It's tough to recommend tooooo much at her age as well.