How To Create Custom Firefox Search Engine Plugin (with Search Suggest).

I would like to create a Search Engine Plugin for the Firefox toolbar, much like the ones which can be found here:

http://mycroft.mozdev.org/download.html

I have seen some guides online about creating text files, placing them in the Firefox directory and so on, but these are solutions geared towards an advanced user.  I am looking to create a simple 'click and install' type plugin which can be offered to end-users of our website.

Generally our search queries are in the format;

example.com/shopping/products.aspx?st=querystring

I would also like to ask for information regarding the image icon, how large it should be and is it a standard 16x16 .ico file?

Some custom search engine plugins have a search suggest feature (e.g google), any ideas on how to do that?

Lastly, it appears that if you visit a website which has a search plugin, i.e. Wikipedia.. then the icon highlights blue (see link for image)
http://img241.imageshack.us/img241/4991/20060925194156en6.png

If you click the highlighted icon, it offers to 'add wikipedia' to your list of search engines.
http://img241.imageshack.us/img241/4416/20060925194304bn8.png

How does that work, do we need to submit the site to a directory in order for the browser to know a particular website has a search plugin you can download and install?Start Free Trial