Typical tip (= to our 15%) for wait staff in Mexico is 10%, more depending on service.
Do not bribe unless you know how. You will get in a lot of trouble. Mexico is trying to change away from the old morida, and if you get the ritous cop, it will not be fun.
The easiest way to bribe if you are pulled over, is to tell them that your are in a big hurry, what is the fine, and could they do you a big favor and pay the fine for you. Then give them extra for their trouble or a little cafecito. About $20 is enough.
Personally, if you have the time, pay the fine. I have been pulled over for speeding, fine was 6$, for rolling a stop sign in was 2$.
US dollars are accepted everywhere but you may get ripped off on an exchange rate. Obviously does not apply to tipping but if your are in the interior of Mexico and pay dollars, you will notice that the exchange rate is about 20% off of the bank rate.
Also, remeber to tip the parking lot attendant a $1 to 50 cents to watch your car. Best money you will spend if in a larger city subject to petty crime.