I like the idea of populating the person field and I think I will use that idea in the form, but I am looking to populate other fields based on the input of that person field. So if Fred is filling out the form he can enter in the name Kim and her information will populate the other fields such as phone number or location. I can already do this with whoever is filling out the form.
I was also thinking maybe I misunderstood what you were saying and the only rule I can apply to a person field is the formatting rule.
This blog that posted is basically how I auto populate my other fields. I just need to filter them by the a person field and not logged on user.