Protecting Your Gamma Site and Distributing Sales Materials Securely

Is it possible to protect an entire gamma site? If not, if I create a site, can I include links to password protectedpresentations? I am putting together sales materials (playbooks, pricing lists, sales collateral) for our partners/affiliates. I want find an easy way to distribute this material and keep it updated, but I want to make sure that only our approved affiliates can access it. Also, if I link to password protected presentations, will they be able to download the presentations? I am open to options here - just trying to figure out the best way to do this in Gamma? Thanks Jason