All tips are paid at the end of your cruise except for room service. For this tip each time you use it as you see fit.
How much would be a reasonable tip for room service be. Sorry, I know everyone is different but I do not have a clue.
A few dollars is fine and would depend on how much you ordered. I always work on the 10% rule but as you are not paying for the food delivered you will have to estimate.
2 dollars is the norm.....Wilba.