"Elle visite une personne malade."
I thought "rendre visite" was used for people whereas "visiter" was used for places. Or is this different because it is not a specific person?
You're absolutely right. I actually posted a comment already a few weeks ago on this subject, but apparently, the sentence has not been changed since.
No, it can't. "une personne" is always feminine, whether or not you are talking about a man or a woman.
Yes, because there is no difference in oral here. However, a liaison should be made between "visitent" and "elles" VISITEU-T-EL