Longbough... wow... I'm completely amazed by the detail and knowledge of your post.
Bravo, from at least one female TFP member here!
There isn't really much to say after that. But I will refer you to a great book that my boyfriend picked up when he was at the very same place as you... just getting started with going down. It has served him (and me) well.
It's great that you are so willing to learn more! Awesome.
She Comes First, by Ian Kerner.
Longbough summed up a lot, but the book is pretty helpful, too. Great illustrations of just how big the clitoris really is (it extends throughout the pubic area, actually) and what you can do for it.
I'll second Longbough on the "don't change anything" part... for a woman, coming is like going up a big roller coaster hill before cresting (the kind where you chug slowly up to the top). If there's any hesitation or change in pace, the whole coaster just slides back to the bottom, or a few notches down if you're lucky. The woman has to "start over" again, in terms of sensations. Yeah, I guess some women might like that, but for me it can be frustrating when I just wanna come!
And yes, make sure you find out whether or not your girl likes direct contact on her clitoris. For me, I prefer my clit to be one of the last things that gets touched... I don't really get wet/turned-on from attention to my clit, right off the bat. Touching/kissing has to be all over my body before anything in my genitals warms up.
Anyway, good luck!! Let us know how it goes.