Too many variables to advise you properly over the internet with so little information to go on. Enlisting the help of a Structural Engineer would serve you better.

We had an unfinished full basement with the washroom on the main floor. Never worried at all about foundations which were cement blocks. No ceilings to crack so I won't comment there. Did have leaks and water all over the floor several times, and that would be an issue for you. As far as the structure, when we moved into a new one story home with the wash room over a crawl space I was worried about the reputation of front loaders for shaking badly unless on solid concrete. I reinforced a part of the washroom floor by screwing a 3X5 piece of 3/4 inch plywood to the old floor in the corner where the washer and dryer were. Then I put in a Hardyboard cement board (1/4 ") on top. Finally we put in a new tile floor using thinset and epoxy grout. No problems now with our Samsung 337. Of course it has anti vibration control.