Cambodia Visa: Took a flight from Taipei to Phnom Penh. I did my visa online but it isn’t really necessary. You can just do it at the airport and the line wasn’t that long.
Screw the buses take a shared minivan: Lonely planet recommended taking the bus. From Phnom Penh to Siam Reap I took the Mekong Express and it was OK. It’s not an upscale bus, it’s an older bus from japan, but upscale bus because they give you a hot towel, water, and some bread. I’d say there is a better option. There are companies that you can buy a seat on a minivan type car. The car is much newer than the bus, seats look much more comfortable and probably faster too. Same price range too. Didn’t know of this option until I was in cambodia.