Hmmm, it’ll be hard to do what you want, most notably the single refuelling station, with just vanilla trains. I used to have refuelling on every stop in a base (main base, big outposts). Then the trains would go between them and mining outposts for example. I’d name all similar stations the same so that it’ll go to the nearest activated station. (Deactivate them when demand has been met). That worked fine for me. Nowadays, however, I use LTN to achieve something very similar to what you have. Instead of trains waiting at the iron smeltery waiting to be dispatched, they now wait in the depot and can go anywhere as long as the wagon type matches the cargo. Gave me the benefit of centralised refuelling in the depot and fewer active trains at any given time. Really worth looking into LTN if trains are your thing. I promise it’s not as complicated as it may look at first. :)