I find it a bit idiotic to try to do a commercial project while a. not having the skills to do it yourself and b. not being willing to pay the people that are doing it.

I do have a few questions did they have you install a software to so you could log in or was their a site to go to? I find it hard to believe they found some way to do this over a site. You need to have a program installed on a. computer so that when a connects to b. it cant do any of the afore mentioned things.

I would personally just recommend setting up a box and giving people group access to the project. They can change and alter it. And just keep a back off site. If someone that is working on the project wants to copy the code then let them. They wont have access to the entire thing. They will only have access to the section you gave them group access to.