Hello, we just got back a week ago from the Serenade of the seas ship. I will try to give a report in a few days.
As to the hot water problem, this is what I did. I went to deck 11 (the buffet area is closed by 11:00 or before), and at the edge of deck 11, you can get tea/coffe or hot water anytime. So I just got a cup of hot water, and added my oakmeal to it, and it worked out fine.