The isolation is probably not very effective if the stand itself is affected by footfalls. You could try moving the stand against a different (preferably load-bearing) wall. Or you could install a turntable shelf.
As for the arm/cart resonance being a little low like this, in my experience it's not a problem as long as your records are reasonably flat, and you can get the table isolated.
As for the arm/cart resonance being a little low like this, in my experience it's not a problem as long as your records are reasonably flat, and you can get the table isolated.