Okay, let's take one qustion at a time:
1) The life style here is real laid back yet hurried at the same time. Taiwanese people are very warm and friendly, so don't worry about that too much, but most are complete workaholics, so they're always busy.
2) The food is, um, interesting. Please, though, don't expect Chinese food from back home. Also, come with and open mind as the presentation of certain foods will be much different than you're used to (ie: heads left on fish).
3) The weather is hot and humid during the summer months, cold and damp during the winter. Fall and spring can be quite nice.
4) You will hear Chinese and Taiwanese spoken quite a bit. Chinese is more prevalent in the north, while Taiwanese is the primary language of the south, but both are common everywhere. If you're worried about English, it depends on where you are. Most people in Taipei speak a little English, but not so much in other parts of the country.
5) The culture is difficult to explain without you being here. It's part traditional Chinese with strong western and Japanese influences, plus some things are uniquely Taiwanese, such as betel nut girls (a must see, by the way)
6) Too many Do's to list here. Just go in with a positive attitude to try new things, and you'll be okay. Some biggies are KTV (a type of karayoke), night markets, hot springs. I wouldn't worry about Don'ts too much, as they are normally very forgiving when foreigners make social faux pas. Just respect them like you would want others to respect you and your family.
7) A great place to be:)
Send me a message if you have any specific questions.