There is no online documentation about these points at the moment
Florian Schwarz and I currently use Linode’s services to host the PCIbex Farm, where the design materials and the results files are stored. So in addition to you, Florian and I (as admins) can also get access to your results files, and probably some people at Linode too, theoretically. If you want to be the very single person with access to the results files, you will need to set up your own servers on a physical machine of yours (otherwise sysadmins can always, theoretically, get access to your files). Alternatively, institutions like universities often give you access to your own space on their own servers, so the IRB might be happier if you can use your university’s resources—you’ll need to make sure you can set up the proper configuration to run a standalone experiment though. See the original Ibex documentation to learn how to set up your experiment on your server.
Let me know if you have any questions