Airports: There are two international airports in Cambodia. One is in the capitol city of Phnom Penh and the other is in the city of Siem Reap.
Visa requirements: You may obtain your visa upon arrival at the two international airports (Siem Reap and Phnom Penh) along with most border crossings. You will need $20 cash for a tourist visa (30 days) and $25 for business. You will also need one passport size photo and your passport must be valid for six month from the date of entry
Note: The border crossings often see corruption. The Thai border at Poipet often charges extra for the visa. Also, many bus companies charge an extra $5 and will handle your visa for you at the border.
Credit/Debit Cards: ATM's are available country wide for MasterCard/Eurocard, Visa, and Dankort.
Price level: Cambodia is one of the cheaper holiday options on the Asian continent. Depending on your style of living and what you are doing in Cambodia, you can stay for a week for roughly $500-$600.
Note: This is for a cheap to moderate stay in Cambodia using local guesthouses and eating local Khmer food.
Tipping: This is not traditionally expected here, but in a country like Cambodia, tips can go a long way in helping people.
Transportation: Buses run throughout the country with fares ranging from $5-$15 depending on where you are going. Taxis also can be hired for travel throughout Cambodia, but are priced higher if you do not share it with anyone else. If you have a large group, vans can also be hired. Tuk-Tuks are the easiest and cheapest ways to get around for short distances.
For more detailed information, you can visit the lonely planet website by following this link.