Hello Rob:
I can help with your questions, which are much easier to answer since you provided good pics and a complete serial number.
(1) S/N V 699640? Based on the info in the Victory Model Database, which my pal LWCmdr45 and I administer, I can estimate for you that your Victory was likely shipped in the October, 1944 time frame.
(2) What does CTG stand for? That is the abbreviation for "Cartridge".
(3) The lanyard ring is missing. Are original's available and where? Yes, lanyard rings are usually available on Gunbroker.com and Ebay.com. Don't forget that you will also need the small pin that will secure the lanyard ring in place.
(4) Stocks appear to be walnut and in such good condition I wonder if they are original? Yes, they are walnut. I suspect that they are also original to the gun based on how they appear to fit in your photo. To find out for sure, take the stocks off. There will be a single serial number, without any prefix, inside the right stock panel. If original to the gun that serial will match the gun's serial. Victory stocks were hand-fitted to each revolver which required that they be serialed.
(5) 4 screws showing, don't know if a 5th is under stock as have not had stocks off yet? Yes, you have a 5-screw gun. (All Victory Models were 5-screw guns.) The 5th screw is located on the forward side of the frame just above the trigger guard.
(6) Yoke has S 5 0 2 7 and I'm not sure if S or 5 is that? It is probably a 5. These numbers are of little consequence.
(7) What is the procedure to get a factory letter? Do you have to belong to SWCA or Historical Society to do that? All that is required is a written request with details on the gun and payment of the fee of $50. Follow this link for the thread by Handejector and click on the blue link that says "factory letter request form."
Information about the SWCA Print that out, fill it out and send it in. If you do get a letter please post back here with the results so that we can add that information to the Database.
Am I correct in assuming that there are no markings on the left top strap of your Victory? It is a very nice example.
I hope this information is helpful to you.