Is there an FAA rule that states the FA has to go over the rules and a verbal yes from everyone seated in the exit row?

The relevant FAR can be found at this link to the FAA's website.

Yes. :0)

+1..

FAs are required by the FAA to do mandatory informational safety announcements prior to flights..

the FA asks"are you able to open the emergency door?" the passenger replies "yes!"

how does the passenger know it is able to perform a task it never has performed before?

trains have kick out windows for emergency. it is my understanding this task is very difficult or impossible for the majority of the passengers.

It's not difficult at all if you read the card in the pocket or glance at the instructions which are usually somewhere on the emergency window/door. The biggest problem is that people don't take the time to read and know what to do ahead of time. I've actually had FAs who ask questions of people in the emergency row like what direction do you stand in to open the window or what are the three things that you do before opening an emergency window. It then forces people to read the safety card.

Last year at the Delta DO in Atlanta quite a few of us did road warrior training and we practiced opening emergency doors and windows. Opening the emergency window was pretty easy once you knew which direction to stand and where to place your hands... One of the things that I came away with is that now I ALWAYS read the directions posted on the emergency exit to know ahead of time how to open the door.

FAR 121.585 does not seem to actually require the cabin crew to personally brief each occupant of the exit row, but in practice they all seem to do so.

While the FAR doesn't specifically require verbal briefing/confirmation, it does require that:

(b) No certificate holder may seat a person in a seat affected by this section if the certificate holder determines that it is likely that the person would be unable to perform one or more of the applicable functions listed in paragraph (d) of this section

In addition, each carrier must

(1) Establish procedures that address...crewmember verification of appropriate seating in exit seats, passenger briefings, seat assignments, and denial of transportation as set forth in this section

and

(2) Submit their procedures for preliminary review and approval to the principal operations inspectors assigned to them at the certificate-holding district office.

If a carrier's individual procedure states that a crew member will verbally ask all exit-row pax if they are compliant with the regs and willing to assist in the event of an emergency, and then obtain a verbal answer from each pax, that procedure basically becomes an FAA reg for that airline.