Imho, you shouldn`t use more than 3 or 4 colours for a page. That may be a bit annoing but 3-4 (like blue, green, black, sometimes red) is quite okay. Also I like this AJAX buttons. If you`ll make somethig alike it would be great and quite pleasant looking.
Don't forget, Mark, that we are developing this platform completely on WordPress. It is not difficult to use AJAX possibilities and features when all your project is built in AJAX but it is not an easy trick to intagrate AJAX with systems that use other coding. However, the task to create AJAX buttons was set for our developers and now they are scratching their heads thinking how to implement this