When we refer to tracks on a loop station, we are referring to the number of channels you can record on and effect independently from each other. As a minimum, we'd suggest going for a two-channel looper, as this will give you a lot more flexibility than single-track units such as the Boss RC-1.
Having two independent channels allows you to record your main idea on channel one and your harmony line on channel two, meaning you can stop and start the overdub at will. This is great for live performances when you don't want all the layers on the entire time.
Obviously, the more channels you have, the more creative you can get with them. Think hard about what you need your loop station to do and make sure you purchase a unit with the number of tracks you need to achieve the desired end result.
When it comes to footswitches, we recommend opting for a pedal with a dedicated stop control. This makes performing a lot easier, and if it all goes wrong on stage, and your performance turns into a car crash, you'll know which button is the emergency break! The single pedal units still have their place, but personally, we prefer a dual button stomp for playing live.