There would be no charge for the usage of the application (and it is free to join up of course).
Once you have decided upon a name if the OP is interested then PM me and I can create a project for you (after that you manage it yourself and I'll be happy to provide a bit of training and support free of charge as well).
The way you'd best structure it is as a Project that has the name of your "group" and then use a Project Area for each specific application (which then contains Project Tasks).
To give you an idea about how this can be used: http://ciyam.org/open/?cmd=view&data=20121221072815393000&ident=M100V137&chksum=45c95736
I will take a look at it in a bit.