Hi Alex
When starting up and buying a HWE carpet cleaning machine here are some guidelines.
Go for a machine with twin vacuums (most use two 3 stage vacuums)
A 100psi pump
A Heater is useful but you can get along without one.
A machine such as this should, with extension hoses, be sufficient to clean an average one storey house without taking the machine upstairs.
Chemicals are usually up to the individual as cleaners seem to get on with some better than others.
Suggest that you do go on a Training course though... there is a lot to learn, many pitfalls to avoid
Regards
Derek