1) You cannot customize the group calendar directly in the hosted system. The main idea would be to download the jacAPI and run that on your own server. There is group calendar and you can customize it there. If you are not sure what that means, just give me the list of property id's you regestired and I will show you what I mean.
Try this link:
http://jhinline.com/apitest/jacshow/calendars.phpThat is the "jacshow" sample in the xmltest of the api download. Customize that file however you like when you run it from your own server. The data will still come from your properties in therentalcalendar.com/jac
2) The open realty is INDEPENDENT from jAC. You do not need to have properties in jAC. Currently this application is free for use on ONE SITE, as long as you give me some feedback on how to improve or fix or make some documentation.
3) If members of your group each register independently in jAC, there is no charge if each user has 3 properties or less.
I hope that makes sense.
John