This article may help its from
www.phuket-info.com should have a look its the lead pages to this forum.
http://www.phuket-info.com/transport.htm
as already said best exchange rate is in Thailand i usally change $50 dollars at airport,then use banks in town,will find changer everywhere,and open till at least 9pm(some on bangla road 11pm me thinks.
try this link for ways to pattaya
http://www.pattaya-at-night.com/howtogo/index.html