Turn your WordPress installation into a feature-rich Real Estate website.
Yes. Google Maps and Walkscore both require you to sign up for an API key in order to access their services from your website. The Google Maps API is also used for automatic geocoding (latitute and longitude) which is used by Walkscore.
Your server is likely using PHP4. Property Press requires PHP5 in order to function. Check with your hosting company to see if they can upgrade this for you.
I have a feature request/bug report form at http://www.pulsedevelopment.com for this purpose. You are welcome to suggest new features and upgrades, and I will do my best to include them in future versions. If you are in a rush, contact me for a development quote.