1/ Consider having a run-through track
2/ An engine service area is almost a necessity. For steam engines you could have an ash pit, a water pipe/tank and a coaling tower.
3/ Add weights to your cars so they weigh about the same. 15 to 20 ounces.
4/ Caboose track?
5/ Are your cars equipped with Kadee or claw couplers? It is much easier to conduct classification operations with Kadees.
John