Flagstone/stone on top of concrete?

We have a concrete patio 25 years old. It has two surface cracks and one deeper one that we repaired by sanding down and filling. The soil below is adobe. We'd like to cover the concrete with stone, but are aware that we don't know if the original concrete is reinforced in any way. We have heard of "Latex modified thinset" as a base then trowel it - then put on the stones on top. We are concerned about movement (northern California & the cracks already in the patio) - so, should we just sledge hammer out the concrete and start over(ugh) or can we move forward? We will likely hire someone to do the work, but we'd like a heads up on how to talk about it so we don't get the wrong information. Any help will be delightful. There are no Lowes/Home Depots near us to ask these questions to. Thanx !