As others have said, though this sounds an insane schedule, it's actually a pretty typical way of seeing Abu Simbel if you're not staying over in Luxor or Aswan. It is definitely a very long day.

When I did this route last spring, there was definitely at least two classes, with the front of the cabin being a typical 2x2x2 US F type seating. (It's possible, that there was both a business and a F, but I don't really recall this. If there was a separate F, I don't think there was anyone sitting in it.) However, as others have said, you don't get much in the way of extra catering or boarding privileges, so it's not that big a deal.

Moreover, at least on the flights I was on, Egyptair domestic Y was very comfortable -- the seat pitch was like old-school U.S. (I didn't measure it, but it must have been a good few inches more than whatever we get nowadays) and width wasn't bad, either. There were a fair amount of empty middle seats, as well.

I agree that the most important thing here is to get a window seat.

Also, though it sounds like you won't need luggage if you're doing this as a day trip from CAI, beware that whatever you have with you when you get off the plane in Abu Simbel, you will be carting the entire time you're visiting the monument (which includes a sizable walk) -- the way the buses from the airport work, you can't leave stuff on the bus, and there's no where to check it at the site.