AJAX custom request into the blog

Hi,

I would like create some customs filter to be able to manage dynamicly the content of the blog:
* Which TAG are excluded or requiered of the Blog Post Request.

I would like to know if GP can provide any filter, hook or something else that could help me in my quest.
I use to perform some AJAX request with a classic theme (not wp), but I don't know how to do the same thing with WP & plugins. Maybe you already get some customers who meet the same needs in the past? I would love to understand the best way to use ajax with GP theme & plugins.

Thanks