Uses shortcodes to display imagemaps with categories of posts.
Just add nopaging=true to your [imagemap] tag. By default, WordPress will respect the post limit set on Reading Settings > Blog pages show at most (which is 10 by default).
This is because WordPress will pretty much encode all characters safely before saving an article. An attempt has been made to deal with the encoded ampersands, but it will only work with PHP 5.1.0 or greater (if you're using an earlier version of PHP, you should be upgrading it anyway!).
Then use the following syntax on the [imagemap] tag:
The number for the category is of course the one used to classify your articles (you can add multiple categories there, too, separated by a comma).
This yellow popup is browser-dependent (but pretty much every browser today has implemented it). To fix it, since 0.3.2, you can leave the alt and/or title tags empty on the [imagemap] shortcode. Technically, leaving alt off is an HTML violation.
Sorry, that's beyond my ability to do. The original source code for the imagemap creator has been done by Adam Maschek, not by me, and I have no idea how to change it to do just that. What I do is to simply copy & paste the existing coordinates on the top part (instead of re-selecting everything). This is a pain if you have many entries, but far better than doing everything from scratch again!
Of course, the Ajax hover box can be fully styled from the Settings tab.