Thank you for the questions. Please see our answers below:
1. We have an additional add-on plugin that caters for high number of markers in certain areas. This is the Gold add-on and is currently avaiable. Please email me at nick [@] wpgmaps.com for more information.
2. Not at the moment, but thank you for this suggestion. Would you be able to email me with more details on what you require and I will consider putting it in the next release?
3. Yes, but through a different method. The starting location of the map is controlled through the settings page. Simple use your mouse and zoom into any area you want the map to be displayed on, and save the settings.
Please let me know if you have any more questions and I'll gladly answer them.