If I am not in First or Business on UA, I am in an Exit Row, so I am pretty familiar with the whole gamut.

As you note, they ask if you are willing and able to perform the functions of the Exit Row. They do this after all the seats in each row have been filled, and prior to the safety demo/video.

On some flights I have seen the safety card slipped up under the headrest in the Exit Rows, usually on the 757 (where 9ABC share a single holder on the wall next to Door 2L so 9B and 9C can't get to it).

I always watch the demo/video, even if I saw the exact same thing an hour ago on the same plane, because I figure the FAs will like to know that at least one chowderhead in the row knows the deal. Actually, on many of an occasion I have been complimented for paying attention.