A combinator to pause trains at stations until the next station is available.
Mods introducing new content into the game.
Entities which interact with the circuit network.
Basically, just hook it to the circuit network, and "close signal" just like any inserter or light.
https://i.imgur.com/d9KCYnd.png
No. There is no way to do this without a mod. Train will choose among the stations with the same name, the closest one. If two train have the same nearest station, they will both join it and wait one behind the other.