Google Maps plugin: adding and modifying it

I’m using a theme that has google maps built in. It shows the listings a various posts I add on the map which is fine.

However, I want to modify what the google map shows. I would like first of all to change the market so it shows a radius rather than a pinpoint position. I found lots of javascripts and code, but do I need to go into the theme functions to change this?

Also, I would like to add a bunch of locations like local bars or restaurants to the SAME map. Is there a way to list positions from google not your own map from the net so its auto updated?

Thanks guys.