in response to your tile problem, i would suggest taking a really deep detailed look and making a decision as to you really want to do it yourself or hire a contractor to do this. It may seem simple but some cases not. Reason i say detailed look is after knocking your tile off and seeing that there is cracking or where tile was being held/gunite is rotted or falling off very easily. The copying/ "concrete piece that is around the perimeter of your pool" may have a seperation joint and was not filled properly with caulking. And water seeps through causing problems in the winter to create the seperation between your copying and gunite causing the crack to then create tiles to fall off. Take some pictures and post them up and see what we are dealing with to better help you