limo question

Hi ladies! I have two questions regarding limos. First, it seems like all places have a 20% gratuity which gets included. Am I supposed to tip on top of that? Second, we are probably going to go with Royalty, however Manny is insisting we need 5 hours when every other place we have been to said 4 is fine for our scheudle the day of the wedding. It seems a little sketchy to me...if we don't use the 5th hour would we be able to get some of the money back?
TIA!