In answer to your questions-- I have two pinhole cameras mounted in bathroom ceiling vents with the power and video leads out to 1) a power source and 2) back to a VCR in my den. (Lots of crawling through the attic to get this done). I usually set a timer on the VCR and end up with a lot of tape to look through to find pertinent minutes. I've recently added a third camera under the toilet in the guest bath and again have run the power and video cables back to the VCR. The subjects you asked about are anyone who chances to use the bathroom when I've got the system on. Usually, thesea are overnight guests, so I am very careful about deleting face shots. Hope this helps.
If you'd like to see more, here's an earlier thread:
https://forum.oneclickchicks.com/showthread.php?t=4187