Concrete pavers tend to effloresce. This is a problem for most manufacturers of concrete products. Attaching concrete pavers using grout or a concrete mix will trap water (when it is applied) in between the pavers causing the paver to turn white, especially around the edges of the pavers. My experience with an "overlay" has given me a new approach. I suggest to cut holes in the existing concrete walkway where the water stands or puddles for a drainage effect before you start your project. Next, lay a filter fabric over the areas you have cut. Then you need to install some (course) washed concrete sand. This allows for proper separation of moisture so the paver doesn;t wick the moisture causing the surface to effloresce. Then lay the paving stones over the screeded sand using an edge restraint along the edges to keep the stones together. You may need to build up to the edges dus to the height difference. This is the only way the you will ensure that you will not get ugly white stains on the surface of the paving stones. Water is the biggest threat to any paving job.

No, in my opinion what you want to do is NOT feasible. According to The Tile Council of North America's, HandBook for Ceramic Tile Installation, that is not a recommended surface. They are the standards all tile manufacturers recommend and installation professionals adhere to. They are tried and true methods of successful tile isntallations. Installing over it, even with a cementious leveler "to fill in the gaps", would probably void the manufacturers warrenties and have a high risk of failure. Will it work ? who knows ... to do so would be rolling the dice in a gamble ... you might win and you might lose.

We had cracks in the patio around the pool after 20+ years and had 1" pavers installed over top. It rather depends on if your cracks are stable. They secure the perimater border pavers with adhesive and then install the field pavers and fill with sand. Paver patios have to be refilled with sand from time to time, but at least the pavers move and don't crack like concrete.

Sorry, just saw your reply. We wound up removing the footings (or, more specifically, we broke off something like the top 6 inches and buried what remained).