Air Travel:
the only operative airports in Cambodia are in Phnom Penh and Siem Reap, even if the opening of SIhanoukville ( Preah Sihanouk) airport has been rumored as imminent.
An airport tax of 25 Dollars is applied for International departures, while the domestic ones are taxed with 6 dollars.
A new national flag is operating some domestic and international flights, here is the link to their website: http://www.cambodiaangkorair.com

Annoiances:
Cambodia is a developing country, so no wonder there are still a lot of beggars around the main tourist spots. A good thing for the wise traveler is to ignore them, especially if they are children.They ought to be at school, not on the streets or beaches.
Given the fact that the educated class and professionals left the country or were killed during the KR era, you can't expect great IQs, here, at least for the time being. If you are just entering your hotel or a bank and a moto-taxi calls you and offers you a ride, don't get pissed off, a good laugh is said to prolong life.