Kevin
When you employ anyone, trust is a very important, so I would tell him the prices including the commercial contracts, if you don't, and he wants to find out what you are charging, then he only has to ask the customer who will tell him even if you have asked them not to.
If you are afraid that he might poach them by starting his own cleaning company, then you can write up a legally binding contract of employment that he cannot approach or clean any of you customers for 2 years after he has left you employment. You can get this made up by a solictor who knows employment law.
As for bonuses, it is always a good idea to pay your staff well, money is one of the main factors in your staff happyness, and un-happy staff are crap workers.
I would pay your staff the minimum wage plus a percentage on all the completed work that they do in the week, any complaints from customers, then send them back to do the re-clean but on their own time.