Cash is the same as what is used in the other games. A hand can start anytime there is two or more people in there, and will be player with whatever number (2 or more) are in there. If someone leaves, then they leave. This is not the tournament variation that gets shown on TV where everyone starts with a set amount and plays until they are out and one person is left.
Limit variation:
http://en.wikipedia.org/wiki/Texas_H...ing_structures