These are really good Alex! Do you use a tablet?
If I could suggest anything, maybe you should try to tackle a single class to completion, then upload an addon. There are indeed a ton of icons in the game, but if you picked a class with limited talents (alchemist maybe?) then you could see the fruits of your labor quicker. I think alchy only has 9 or 10 trees, which would mean that you could complete it with 40 icons. Then you could see your fleshed out hotkey bar.
I'm working on a similar project myself, but using the stock icons and enhancing them with brighter colors and color-coded borders for each tree. I find that when you have a hotkey bar full of talents (60 or so at 32x32 icon size, two rows deep) colored borders help your eye pick out what you're looking for a lot quicker. You could keep all the detail in your icons if you re-sized a 64x64 icon to 60x60 or 62x62 and added a border in the empty space. If you wanted to go this route, I recommend resizing to 60x60 which would leave a four pixel border on each side. This way, the right click menu (which uses 16x16 icons) would have a full 1 pixel border. I don't want to clutter up your thread with example pics, but I hope I'm doing a decent job of explaining what I mean.
Of course, you don't have to use my suggestions, your work is really awesome as is. I can definitely see the Warcraft influences. Good luck with the rest of the project and keep having fun with it!