please have a look at this thread:
There is also a sample file that you can download.
If you try to adopt this for your data it is very important to have a careful look at all chart settings.
Regarding the auto zoom, I found it!
The one responsible for the original script had saved the longitude and latitude in a table as Longitude and Latitude. But in the google map script, they were referred to as longitude and latitude. So, a little change in the variable names solved the zoom problem.
Regarding the pan situation, the sliders suggested in the example seems to the right way to go, thank you for that link. I've already implemented a slider for zoom, so they shouldnät be a problem.
Thank you for the help,