Sorry you are not bringing this to York. I would loved to have seen it and would love to study it closely. I wondered if there are any model markings on the train and box. This is a US Fandor conversion with appropriate cowcatcher pilot and bell added for the US market. It looks like a 20 volt Fandor 1603/5 Set from 1929, which is the earliest Kraus catalog I have ever seen and have access. The cars were popular in several steam and electric loco sets and were the 1211 Packwagen or Baggage car (1926-1932) and the 2 1210 Passenger cars (same dates). Of course the PENNSYLVANIA RAILROAD markings are for the US market.
I believe the light bulb is a resister, but without testing it, I can not be sure. It also would indicate power to the unit. The screw in adapter was common in the Pre-1930s and was used to screw into a lamp light before there were standardize appliance electrical plugs. If there were plugs available, you simply removed the screw adapter. There is a track connector unit. Most sets would have come with 12 pieces of track but this set box does not look to have space. You are correct that the clips are to hold the track together.
There is a similar boxed freight set on ebay for under $200, although the engine is incomplete. Your box is good with the exception of the torn label. I would price your set at no less than $500 and perhaps more and would enjoy purchasing it from you if you would like. The set would find a home with its other brothers and sisters. My favorite is a wooden boxed set which is very early.
I love the history of Krauss-Dorfan. In 1936, Hitler took ownership of most of the train manufacturers in Nurenburg, which was also home to the Nazi party. Nurenburg was the capital of the world's greatest toy train manufacturing and most of it was owned and run by Jewish entreprenuers. You can only guess what happened in the 1930s to many of them. The US leveled Nurenburg in WWII, not to get to the Nazi party but to stop the old train factories which had been converted to munitions works. The story goes that Josef Kraus was given advice that he was in danger, and he left Germany to England and later to New York where he united with his cousins and friends at Dorfan. It would make an interesting study what happened to the families of these famous train manufacturers (Bing, Bub, Fandor, and a long list of companies), but not Marklin in Munich) that remained behind. I took a trip to Nurenburg to find the Kraus factory which was reported bombed in WWII, but we found it. There is a museum in Leipzig, Germany where an extensive Kraus collection is housed, a gift from a prominent German collector who is on the Dorfan Facebook site and gave me information about the collection. I have to make the trip, which would be challenging at my age.
if you want to have more money to spend at York, let me know.
John Wheeler 412-352-0471 dorfanman@wheeler.net