Ok, to add some more,
Doing revolvers or pistols, new or old, SA, DA or SA/DA is really not a problem. Personally, I like to have the complete handgun when it comes for Cerakoting. That way, I disassemble it, Cerakote it and I reassemble it, that way I know that it functions correctly before going back to the customer. I have many books that show the breakdown of even old revolvers and pistols and many times I will take pictures to remind myself how the parts go back together. I have never had a gun apart that I couldn't get back together (I learned my lesson early on

to make sure I have a good exploded diagram, or a assembly/disassembly book or pictures). Also, if the Cerakote changes any dimensions where pins/screws go, I know that and can fix the situation before returning it.
As for the prep, anything getting Cerakoted needs to have a roughed up surface (and by the way, you can Cerakote anything that it will stick to, including wood). The typical way to roughen the surface is to blast it (etch) with aluminum oxide. I used 120 grit or finer (depending on the firearm). Glass beads will not work because they do not etch the metal. Once it is blasted it is soaked (normally in acetone or another degreaser) to remove all the grease/oil and then heated to make sure no grease/oil remain. You do a final soaking/cleaning and let it air dry. Once completely dried, it is sprayed and air dried for about 10 minutes and then cured in a drying/curing oven for several hours at different heats depending on the material (polymer frames get cured at a lower temperature to insure they don't warp).
Nickel and chrome plated guns will accept Cerakote, they get blasted just the same as any other metal. If the nickel or chrome is flaking off, you need to remove as much as possible before blasting. The blasting should remove any other loose nickel or chrome material as well as any rust. Blasting WILL NOT remove deeper rust pits but it will remove any rust in the pits. The pits will show up after Cerakoting and if they are real bad, they can be filled with something or even welded if extremely bad and deep, then smoothed to the contour needed.
If the nickel or chrome is intact, you blast the parts to be coated and clean them as normal and then coat. The Cerakote will seal the gun so that nothing can get under the nickel or chrome so it shouldn't flake off (I've done two so far and they've been fine).
Here are a few examples of Cerakote. I have done other SA's but that was early on and I was stupid and didn't take pictures. I have Cerakoted older Taurus revolvers and pistols, S&W J frame EDC guns, Colts (no SA's though), Rugers (of course), Rossi's, Old WWI and WWII pistols (not collectibles), European pistols (knock off's of Brownings and Colts), and many others and I have had no complaints so far that the customers were unhappy with the Cerakote.
Here is a before and after, this one was pretty bad and you can see in the after picture that you can see the pits but it still looks pretty good. A customer brought this to me and it became his EDC gun after he got it back.
This Colt was hard to put back together just because of the way they are assembled. It did have to go back to Colt because of some other problems that I just could not get worked out. They did the fix and returned it to me and I sold it; I shouldn't have

:
This was my first Glock, I did this because I was tired of all black guns:
I've been doing this long enough now that I completely trust Cerakote to perform as it is advertised as long as I do my part in prepping the guns correctly. Not one of my customers that have had guns Cerakoted have ever complained to me about it and these are long time customers who will let me know if they are not happy with something.