The AC already planned to include and upgrade the existing Caucus railway in the newer network. It would be advisable though (you can figure out the feasibility yourselves) to have a full circuit railway system running from Bath'al to St. Fydorsburg to Vålderesk and back again to Bath'al. The way it sounded, there was some issue with a transcontinental railroad going from the main population centers of Belsnia to Erinaum; but if the distance obstacle can be overcome there I should think it'll greatly increase the efficiency of the network. I'm sure that connecting a few Erinaum lines to an upgraded existing network would function as well. Just throwing it out there.
Maybe. Have a look at
this.
I think the line should arrive at Sånyéta. It can have large capabilities as far as shipment and stuff. It then can travel to Nimun, already a huge, industrial city, or go directly to Vålderesk. This can form a triangle that allows for efficient distribution and even have an extension go to Ütœ ê Kïter, a town in Manchuria that holds much mineral wealth. As far as looping it back around, I am not sure that is a good idea. Mikoyan already said that running a line through Belsnia would not be profitable, and certainly not reliable in winters. The area isn't very populated, which means that he'd have to throw money around to ensure that people will create a LOT of service stations. I am not sure he is willing to do that. The next option is to run the train through Mongolian Wilderness. This land will have to be claimed in order to ensure the train's protection, especially with the possibility of a country moving in there. Another option is to run the train through Tibet, which would be a very costly project, and would take a decade at least. When completed, it could possibly serve as a loop, but in the near future, that seems like a bleak possibility. The fourth and final option is to make the railroad two-sided, and have many points where there are three or more rails to allow trains to pass each other. It also allows a single customs house to be built in Sånyéta.
I think this should be the main route, and any other rail lines can be built around it.