Currency? Cambodian Riel is the national currency ($1USD=4,000CR) but the de facto currency is the US dollar. CR is used for change under a dollar, so just bring USD.
Visa required? Citizens from most countries can obtain a 30 day e-visa or visa on arrival for $30USD. If you are getting one on arrival it may be worth bringing a couple passport pics to save time.
Weather? Tropical, very hot. There are two seasons in Cambodia; dry and rainy. The dry season generally runs from early December to May. But it should be said that the temperature during April and May can exceed 40. The rainy season typically starts late June and finishes in late November/early December. Be warned: it rains like crazy in Cambodia at the height of the rainy season.
When to visit? Between December to February would be the ideal time to visit when the weather is sunny, mid 20s to mid 30s, and very little rain
Food? Their food has been influenced by Vietnam, Thailand, and India primarily. Expect curries, BBQ meats, seafood, spring rolls, and fruits. My personal recommendation is fish amok, a fish/seafood coconut milk based curry. Thai, Vietnamese, and Indian restaurants are also abundant. If you are so inclined, try the ‘happy pizza’ made famous by Anthony Bourdain.
Alcohol prices? Most local cans of beer are $1, bottles might be a little more, and happy hour draft beer often goes for 50 cents! Cocktails start at around $1 or $2 and are often buy 1 get 1 free or at special prices for happy hours.
Top destinations? Phnom Penh, Siem Reap, Sihanoukville, Koh Rong, Battambang, and Kampot.
National holidays? Lots of national holidays but hands down the biggest is the three day celebration Khmer New Year, celebrated mid-April around the same time as Songkran in Thailand.
Top backpacking experiences? The majesty of Angkor Wat, firing an RPG or an assortment of other Cold War era guns, the Killing Fields and S-21 in Phnom Penh (heartbreak alert), the parties of Sihanoukville, the serenity of Koh Rong, endangered Irrawaddy dolphin spotting in Kratie.