Guns and More,
Here are the answers to your questions to the best of my knowledge.
The Early Pre-Production Guns (No R Prefix):
All of these guns were marked "Farmingdale, NY" had blue CF grips and if the gun had sights were marked with "R9s" on the slide. These guns also had slightly thinner walls on the slide. Of these guns only two had silver frames (#223 & #321).
#'s <= 100 were reserved for the factory. (#1 is Karl's gun, #2 is Eric's, #33 is one of their investors, I'm sure there are others. I am not sure if all the frames were actually made or if the numbers are just reserved.)
#101 was a presentation gun given to an early supporter of Rohrbaugh on various web forums - he still has the gun to this day.
#102 was the first gun sold to the public and has sense returned to the factory and is on display.
#103-147 went to people who either had been on the wait list since the very beginning (i think over 2 years for some) or were prominent gun bloggers etc.
Custom Numbered Guns:
"R9" Karl's personal carry gun for many years with blackish frame, blue grips and no sights.
#221 & #223 are the guns featured on the cover of the manuals. #223 is a silver frame with sights and #221 is an early grey frame with no sights. I don't think these guns were sold to the public.
#246 has a darker frame almost black with blue grips and sights.
#321 is a silver frame that was originally marked #148 but was given the custom number 321. I believe this is the only silver frame pre-R sold to the public.
Other custom serial numbered early guns include: "Blackhawk-1", "NRA-04-001", "BPD-001", "DTM39", "David-1"
The Production Guns (R Prefix):
The "R" prefix was added when some minor Revisions were made to the slide (thickened) and possibly some other internal tweaks. Numbers were started over at "R101"
#<=R100 were reserved for the factory, again I don't know if all the frames were made or if they just reserved the numbers. "R101" is has been referred to as the first "production" gun after the initial revisions.The grey anodizing on these R Prefix guns is a bit darker and less "plum colored" than the pre production guns. A few hundred of these R Prefix guns were made in Farmingdale, NY before the factory moved to Deer Park, NY. They produced about 600 total sets of blue carbon fiber grips (including the ones used on the pre production guns) so a lot of the earlier R Prefix guns will have the blue carbon fiber grips. This is also the time when BATF instructed Rohrobauh that they could only use the "R9" designation on the slide regardless if the gun had sights or not. Since the frames and the slides were hand fitted together some of the earlier R prefix guns with sights will have the "R9s" designation while others wont. There are no hard cutoffs serial number wise where before a certain number you would be guaranteed to have a Farmingdale, or blue grips, or the "R9s" designation it just seems to have come down to the luck of the draw - there are some pretty low Farmingdale, NY guns with black CF grips, and there are some pretty late guns with the "R9s" designation. For the most part though the lower the number the better chance the gun has more of the early features. There were also about 12 silver frame guns made in the early R prefix period- it was difficult to get the silver anodizing correct so only a few guns were made before the factory no longer offered the option.
Later guns with R serial numbers in the high hundreds and mid to low one thousands had slightly darker frames (this is my favorite frame color) and black carbon fiber grips. There were two styles of black carbon fiber grips; the later style has a diagonal pattern to the carbon fiber. This is also the serial number range where the factory got a bad batch of steel for the slides and had some cracking issues on the back of the slides. This is fixed under warranty regardless if you have the warranty card or not.
The frame color was then changed to black for both the two tone and the stealth and G10 grips replaced the black carbon fiber.
