Orinoco

Looks really good. What are you planning on doing for windscreen wipers? (just out of curiosity - not a criticism)

Paddock Wood Bay sounds like it is at the seaside

Looking very good!

Only just seen this. Dundee is a very neglected area for models, yet very interesting. In former times, East and West stations and the dock railways were also fascinating. Looking forward to seeing more of your plans and modelling.

Older wagons can always be parked in sidings. You don't have to run them all the time.

If the 3D printing is not reliable, you could try making the centres slightly undersize and build a jig to get the wheel centre (based on the axle hole) and tyre concentric. Use adhesive to fill the gap.

Just a very small point, but the Jersey Eastern Railway 0-4-2 tank locomotives were built by Kitson. Nice idea though, all the same