Yes you can. You will need to open up the asset in Content Manager for editing in windows and add some lines of code to its config.txt file.
Passengers will then load and unload at stations, with graphic people appearing and disappearing on the platform. However, as the asset will have no attachment points built in by the original designer, you will not see passengers sitting inside the car.
Yes, I believe it is possible to do that using a similar method to that used to activate passenger rolling stock. But without attachment points built into the station asset you will not see passengers standing on the platform or appearing/disappearing as a passenger train loads/unloads at the station.