Resurfacing problematic pool

Hi,
Hoping to get some opinions here as I've had several "experts" with differing recommendations.

The problem: I would like to have my gunite pool marble dusted, but when investigating this quickly learned that the newish paver patio was installed over an old one. As a result, there is a 3 inch vertical gap between the top edge of the pool and the bottom edge of the coping. The gap appears to have been filled in with cement/mortar, which now has a 1/4 inch crack running through it around the perimeter of the pool. A row of 6 x 6 tiles runs just below this gap, which need replacement.

I was told that the patio/coping was done incorrectly. In addition to ripping old the old patio, the coping should have been installed in such a way to prevent water from entering, which is what caused the crack.

The proposed solutions have varied but my questions boil down to this:

1) Can the new tiles simply be moved up from where the old ones were and then marble dust the whole pool including the area where the tiles used to be? Or, would it be better to tile starting at the bottom of the old tiles but extending further up (8-9 inches instead of 6).

2) Coping will have to be removed and replaced. In order to prevent water from entering, freezing and causing more cracks, does the coping need to extend out 12 inches from the pool edge? Some have recommended this, while others say to replace with another 8 inch stone but include an expansion joint between the coping and the patio.

I'm thoroughly confused at this point. Thanks in advance!