welcome to P.R.China. i feel amazing that i can log in this website from china！
firstly i'm sorry for my poor English;)
Are mainland Chinese web sites usually in simplified Chinese or Pinyin or neither?
——Yes, mainland Chinese web sites are usually in simplified Chinese, maybe websites of companies are in both Chinese and English, but no pinyin at all.
Do you have to have your site physically located or hosted by a mainland Chinese provider to get indexed by Baidu?
——sorry, i don't know.
by the way, maybe you cannot visit "you tube" "twitter" and "facebook", so far i have not visited them successfully. AND, i'm not scaring you friend, the food in china have got many problems, such as fake foods, poisonous rice, man-made plastic eggs, and years ago milk and drinks had problems too. recently, the oil for food becomes a big problem, some people make oil from rotten food and internal organs of animals.
HOWEVER, many Chinese girls like western men, especially in big cities such as Beijing, Shanghai, Guangzhou and Shenzhen...i think mainly beacuse they think western men are rich.
I'm a Chinese, and replying you just in China.
but l do like America better, the environment and traffic seems better than those in china。 if i have enough money, i would move to US or Canada..