Please can someone tell me if I develop an App for Cydia is it possible for the app organisation named Sinful to copy it and place it on Cydia for free as they seem to be able to do with other cydia apps?
Also where are the rules and regulations and development kits for app development for cydia?
It's possible that people could pirate your packages. It happens. Some developers choose to ignore it and some choose to develop copy protection methods.
The best place to start for those questions is probably by reading the unofficial iPhone Dev Wiki.