No problem for Dollars and Canadian Dollars exchanges to pesos, but the British Pounds may be. The airport Bital is once again the best place to exchange any currency, including pounds. Next best are the large exchange houses such as Monex and Intercam. Or your local hotel might. Expect a slightly lower rate for travelers checks.
Cash is king.
Exchange fees are generally not charged. This way you will arrive in Mexico with pesos for cab fare to your hotel. Generally speaking, tip as you would back home. The water in Puerto Vallarta is one of the best in all of Mexico, and purified water is used extensively in hotels and restaurants. Bottled water is readily available and inexpensive.