David E pretty much covered all the bases. I can only add some caveats:
Your lady will likely hold you to your word, and not necessarily what you meant, but what you said. She will be greatly disappointed when the million RMB you promised her parents is actually a thousand.
I found the local doctor very professional and thorough, but I would not want to visit a hospital unless it was a true emergency. My wife caught a rash while staying with her sister in the hospital for 4 days. David's right (as always), health insurance is almost a must. Don't take the chance.
Squat toilets are hard to get used to, but surprisingly, once (if) you do, they seem to make for easier bowel movements.
The differences are surprising between China and the west. It's almost like EVERYTHING is different that can be different. Customs, tastes, smells, sizes. It's like they see something in the west, and deliberately do it differently. But I'm sure it's us that are doing things wrong.
China is beautiful and friendly. I've never once felt unsafe. Go with an open mind and a friendly smile, and you're sure to have a great time.