Dave pretty much summed it up. If they had a smoke unit most were Suethe non puffing types. Maybe a few at the end had fan units. Gearing can be all over the map. My Hiawatha Baltic 4-6-4 has 44-1 gearing so runs very slow, especially for a passenger engine. Gearboxes can be swapped out though. Also realize not all steam engines are brass. Some like their 2-8-0s are diecast.
Pete