By far the best resource or reference for a prospective car engine shopper looking for a Cummins engine is the Cummins site on the web. Other options include Diesel Rebuild Kits.
Cummins is made by Cummins. They are one of largest diesel engine manufactures in the world.
Only one fuel filter
On a Dodge Ram 1989-2012 have one, 2013 has two.
Every one I've dealt with had a capacity of five gallons.
Most any mechanic shop would have one.
Ford does not own Cummins or Cummins "patents". If they were Cummins patents they would belong to Cummins. Cummins may well license patents from Ford, cross-licensing is common in industry, and there would be nothing unusual in that. Ford did own some Cummins stock in the past, but Cummins is an independent company with plants all over the world. This is a rumor that has circulated for years, partly because of an old internet hoax. Ford does use a Cummins in one of their heavy duty trucks, I believe, but their main source of heavy duty diesels is International.
With no idea what you are doing it would be a learning experience and an expensive one. I would suggest purchasing a shop manual for that vehicle and owning a full set of tools and some shop equipment.
Depends on which engine you have. Cummins engines typically have two. Cats can have one or two.
One can purchase Cummins tools from many retailers. One can buy them from 'eBay', 'ToolsNow', 'Apex Tool Company' or one can buy them from the Cummins store on their website.
A Chevy 454 engine can be obtained when one goes to a Chevy dealer, an auto shop, or a body shop. The engine is a pretty good one as it delivers 240HP and 355 torque.
Local auto parts stores do not typically carry a Transit engine. One can be purchased already in a vehicle at an auto dealership or ordered online from a number of sellers.
One of the most popular is the Cummins ISX--15 liters displacement, anything from 435 to 600 horsepower.