I had always assumed that it was Uriel that did it, all things considered.

It's ... totally something that he'd do.

are the faith powers internal or external?

Yes. To me it's a combination of both.  There must be an "external power source", such as the White God, or Magick itself. And there must be the strong conviction in that power to be able to influence the world.

Human Form definitely works better than Guise for what you're doing. I have a player that shifts into a gruff type fae in my own campaign and did some looking before allowing it. 

Guise is for something that looks almost completely human. White Court being the obvious example, but Ghouls being the other.  Very close.  The big distinction is that, in Guise your powers are still available, but as soon as you call on them, your nature is revealed.  Human Form, you have to "shift" to gain access to them. 
So the question is, always accessible or have to change forms to gain them?  If change forms, then Human Form, else Guise. 

Personally, I'd say screw the item approach.  It's a simple ritual. Just requires something significant to the "destination", or otherwise symbolic.  4-5 shift seems appropriate. Call it a mild divination. Or some such.

IIRC, the first book mentions or WoJ mentions that it is an alternate timeline. Partitally written by a "earlier enlightened billy". So it's not entirely cannon (after turn coat it, IIRC).

Repeated thread. its come up thrice now.  Officially, its "Paranet" stuff. IIRC

Just FYI, it's not fae disgusing as aliens.  If you look at a lot of the "newer" alien abduction/encounter/spotting stories, and you look at a lot of the old faerie stories, you *will* see a *lot* of similarities.  Faerie lights? UFOs.  Little green men? Nixies maybe.

Basically, the stories *evolved* because science and understanding of the world did.  You think we'd have *aliens* if we never took off into the air? Or space?  And how much of our mind fills in blanks?  A forced sexual encounter with a fae turns into "probing" because that's what extraterrestrials would do.

In a lot of "mythological research", the general conclusion is that aliens == fae and fae == aliens. 


And as for the NN on other planets: Personally I'd say it's there.  Maybe not anywhere as strong. Where a 4 shift effect is needed here, maybe it's 20 there. (world walking part of thuam)  And as for Seelie and Unseelie courts. Maybe there is a greater balance there, or shared domain (no seasons, constant all around). Or each court owns permanent claim on certain sections, as they're constant temp all "year" round. 

Or maybe there is an alien race. Using the NN as a sort of hyperSpace for FTL travel.

The books mention jails at one point. But dood, that school janitor is totally going to get you. Lead by the Principal, naturally.
But malls would be a good place too. And Starbucks.