When they ask your fee, you can quote a figure and say something like "We usually get "x" amount but we'll work with the client's budget if we can". Or, ask them "What is your budget" and then that gives you an idea. That lets them know you're open to reasonable negotiations.

Re: Tipping the waitress - maybe tipping isn't the custom in Canada, but in the US if the waitress brings you drinks, food, etc. they should be tipped. Tips are considered part of a waiter/waitress' pay - they don't make much of a base salary.