Re: D&RGW Long and Short RPO Cars

#1 Yes, both the 60 and the 122 had a five window configuration, three on one and two on the other.
#2 (Post 1923) Short cars were 53, 61-63, 118, 121 and 123. Long cars were 54, 60, 64-66, 119, 120, 122. Eash car was a little different, but fortunatly, 10 of these cars are still in existence, so you can go to Dave Dyes site for pics, or see them yourself, or try to ask for the kindness of the group for some pics.
#3 At least the 53, 61-63 had 2 windows per side. The 118, 121 and 123 were different, the 118 being an ex business car, which I don't know of any photos, and the other two were old baggage cars, and the 123 is at Cross Orchards with the Uintah equipment. I believe it had four windows per side.
Note: The 118, 120 and 123 were used in work service, so I can't verify the window situation, but it appeared that the 120 and 123 had odd configurations, as the D&RGW didn't tend to make new windows on ex passenger cars that became MOW.
I can help much on the windows, but looking at pictures of the cas is probably the best way to tell.
I hope this helps.