Cheapest ride to Wattay International Airport (4 km away) is to catch Bus 49 (4,000 kip; 6 AM to 5 PM only), or a passing shared tuk-tuk (5,000-10,000 kip) at Samsethai Rd near the tourist quarter.
Withdraw money from the actual bank branch to avoid getting your ATM card captured (makes it easy to retrieve it later). Also the ANZ ATMs let you take out 2 million kip.