At it's heart, photoshop is a bitmap editor it's original purpose was for manipulating photos various tools have been added with new versions that make it more useful for web design.
Illustrator is a vector-based app for creating free-drawn illustrations. Again newer versions have added things like pixel snapping to make it okay for web design (but its better suited for logos, visualization etc).
My preference is Fireworks. It's got great exporting tools and I find it a lot faster than working in Photoshop (for web/mobile work).
Remember also that design involves a lot of iteration. If you're concerned with efficiency, please get comfortable expressing your ideas with pen and paper - it's the fastest option :)
One thing I would add - I noticed a few clumsy typos in the slides and in the title of this very post. Please do proof-read your copy before you publish for your app. It probably doesn't matter as much here, but I think you can ruin your carefully designed professional impression with just one or two misspelt words.
"There are only a bunch of fonts that designers use." This really isn't true. There are about a hundred or so that are particularly common that any good designer should be able to recognize on sight, but there's an enormous long tail, many of which are perfectly servicable for specific uses.
"Corrections at this stage will generally be minor" Your interface's visual corrections may be minor, but in terms of usability, information architecture, and so forth, if you haven't incorporated results of real testing by this point, you're in for a real suprise. Especially if you're not versed in design and usability literature, you're likely in for either a lot of frustrated users or a lot of reworking.
I'll also just point out, while I'm at it, that on your screenshots page, your Facebook icon is next to the word "Twitter," and proximity implies association.
If you're really looking for a good grounding in HCI fundamentals, The Design of Everyday Things, The Humane Interface, and, oddly enough, the OS X Human Interface Guidelines are among the best. For type, try "The Elements of Typographic Style," and for a basic, general overview of some concepts you should understand, "The Universal Principles of Design" is, well, not bad.
Is it a particularly hard thing to do? Is it news-worthy? I really don't think so.
Good luck with your future work.
As someone who's a novice programmer, I'm impressed. I'd also like to learn the fundamentals of design.
Anyway, good for you and nice slides!
