I have an all-DCC system. The turnouts and the crossovers work fine, and I don't mind controlling everything from the EZ Command unit.
If I buy a powered accessory (station house, lighted caboose, road crossing guards, etc.) do I power it by plugging into a jack on the terminal?
You cannot use a dcc system to power those accessories generally. You can use any old power pack to power those.
Many inexpensive power packs available on Flea Bay for such purposes.
Thanks!
Your lighted caboose will get power from the tracks.