2. F isn't enough. F of what? I believe it should be Fr for Force of Resistance.
In this particular problem, the resistive force was DEFINED as "F." So the plain old label "F" is okay here. But generally, Mr. Moyler is correct -- put a subscript or words on the label on a free body.
Another student, Frederic Lamontagne, followed up:
Firstly, there is no normal force when the object is on water. The force on water is Buoyant Force. Secondly, [this force] would not be acting to the left (as it is indicated in the free body diagram)...it would act perpendicular to the water.