What size motors and how many dc does it run on
Model railroad motors are sized for the application - they aren't really "HO motors" or "N motors". All of them in the U.S. are designed to operated on 12 volts DC. Most modern motors only draw a quarter amp or less, so you can operate several at the same time from one power pack.
usher-
ebtnut is absolutely correct. The choice of motor to install is driven by size more than power considerations. And by power I mean pulling power, not the electricity on which the motor runs.
-- D