Faleolo International Airport (APW) is 35 km west of Apia. Schuster's Shuttle Bus will take you right to your Apia hotel, or you can wait on the highway for a public bus, which is cheaper, but very scarce after 1600 and on Sunday. Airport-bound, the airport bus departs Apia two hours before the flights. It picks up passengers in front of the Hotel Insel Fehmarn, then at Aggie Grey's Hotel.
The airport taxi drivers often try to overcharge foreign tourists, so take the bus if you can. A taxi from the airport to Apia is around S$45 (45 tala) for the car but they will often insist on being paid US$45 in American currency, so be careful. It's much safer taking a taxi back to the airport, since they'll know you're already familiar with Samoan currency and probably won't try this trick. A taxi from Apia to the airport should cost S$35, but expect to pay S$45 early in the morning or if you booked through a hotel. Samoa Scenic Tours at Aggie Grey's Hotel does airport shuttles.
The banks in the arrivals area open for international flights (excluding those from Pago Pago) and change traveler's checks at similar rates. Ask about commissions as these can vary dramatically with the greedy ANZ Bank usually taking a lot more than the Westpac Bank. An ANZ Bank ATM is available.
The Western Union office at the airport charges less than the banks to change traveler's checks and takes no commission on cash. For changing excess tala back, the banks in the departures hall are open for all international flights except those to Pago Pago. There's no left luggage room, but there is a tourist information desk. In a pinch, you can sleep on the floor upstairs in the terminal.
The airport post office (weekdays 0900-1530) sells philatelic stamps, a good way to unload excess tala. The duty-free shop in the departure lounge sells only expensive luxury goods and imported alcohol, so don't wait to do your shopping there. In general, alcohol and beer are relatively cheap in Samoa anyway.
The international departure tax is S$40 (children under 12 free). You don't have to pay the tax if you stay less than 24 hours (transit).