Next, if you are referring to your original function , I think it has been made abundantly clear we are not doing anything with amplitude. With respect to the other function, the sin(stuff) function without the vertical shift and without the 25/4 in front of it, that one DOES have an amplitude of 1 (max y at 1 and min y at -1).
So far, I've been focusing on just the graph and behavior of the functions we talked about. I didn't even look to describe how to answer the questions.
My main thing right now is that you understand what's going on with the interval and the function in question.