re: I would also like the community to rate and write reviews on the service providers.
Sorry, no, there is no review and ratings extension for Connections at this time.
re: Better yet if we would see a TOC of provider categories
In the Widget Pack there is a category widget that you can place in the theme’s sidebar. This widget outputs a list of categories that when clicked will take the user to the directory home page filtered by the category that they clicked. They can navigate the various categories simply by clicking the link in the category widget. If you decide to use the widget, you should disable the category drop down on the template so they do not conflict.
Hope that answers your questions thoroughly!