Hi Carl!
I'm again short on time, so I'd just like to elaborate on your questions:
1. What color scheme do you think we should go for?
I think the colors of the logo and our current default theme give a bit of hint: I'd like to stick with blue-grey colors. It should look solid and trustworthy, not too "playful" or misleading.
2. Should it bea basic, or more advanced theme? Do you want it to showcase serendipity, or should it be considered a training tool for new users who want to develop their own theme?
I'd like a theme which works well cross-browser. So probably not too much freaky CSS/JavaScript stuff. It should be flexible and not cause a hard time when manually modificating it, but that's only a minor point.
Priority should be a decent look without buggy appearance. And it should use the currently existing CSS/HTML selectors, if possible. This ensures that it works with all plugins that use custom styling based on those selectors...
3. Should it also include a new admin suite?
I wouldn't mind! Surely the backend is only styleable via CSS only, but I think a lot could be done there as well.
If needed for good appearance, we can talk about modifying the HTML output there as well. But a smartyfication of the backend is very, very hard. Especially in terms of maintaining the admin backend for future versions and new features.
4. Will you be changing the serendipity logos?
If there is a logo that takes my breath, I wouldn't mind. But as Judebert also pointed out: I, for myself, enjoy the s9y logo and haven't yet seen a better proposition
5. Do you want the stylesheet to explicitly mention all styles used by serendipity even if they aren't in use within the theme, and should the stylesheet be commented?
Commenting would be helpful. But implementing all (empty) CSS selectors is IMHO not required.
6. Do you want to leave the smarty template files the way they are, or could we change them?
They can of course be changed, but not majorly. You need to think of that all other themes use the Smarty files of the default template if no custom file is existing. Changing the default Smarty HTML too much would break all depending themes, so this must need to be performed sensitively.
Adding/enhancing styles shouldn't be a problem, but BC should be held. One of the great things of Serendipity is that we pay a LOT of effort on maintaining BC.
Hope this carries on the sparkle you started, Carl!
Best regards,
Garvin