A lot of times we tend to do something simply because we know it can be done and don't have the slightest idea how to do it successfully. With the technique of cutting out a wedge from the trunk in order to bend it, there are several things that must be done carefully and accurately or the process will fail and you may lose the tree. As to planting the tree on a rock harvested from a salt water source is generally considered a bad idea. You don't ever seem to get all of the salt out no matter how you wash and soak and fool around with the rock. Generally speaking the only rock artistically acceptable will be rugged having many furrows and caverns in it. These places will harbor salt and may not be salt free in either of our life times.