1. Yes, you can install it on a subdomain. Please take note that Classipress is a Wordpress theme.
2. The theme is not encrypted and so it is open for you to check or modify.
3. A knowledge in php, html, css and java will definitely come handy in the maintenance of the theme.
Please help our moderating team work more efficiently by not sending us support questions via PM. You can read more about how AppThemes support works
here. However, you can send a PM to follow up and remind me if I missed your support request/thread.
Thank you and have a nice day.
