How many locos can I run?

Q:  I want to buy the Zephyr. I have read the manual, read articles on the Tech Support Depot, but I still find it confusing. So, here's my question: Can you run multiple trains at the same time with the Zephyr, without additional throttles, each locomotive performing a different task, and if so, am I right in assuming that this can be done by punching in the locomotive address, adjusting the throttle and direction, and when I punch in another address, the previous locomotive will keep on doing whatever it was doing until I punch its number again and change ...