I have a broken and uneven concrete patio - I don't want to remove it - I want to cover it with a wood deck... it is fairly stable - can I just put in small posts and level it and use it as a base for the new patio ?

You can build over it, but you should try to get your support posts outside of the patio area so you can bury them deep enough to be past frost depth.

Amricca has spelled it out correctly. Your deck must be supported on its own frost proof post or piling.