Salamander20 - You can buy all the tickets you need for the remaining of your trip. You would need to book a seat with exact date and time though. This requires good planning for your commute to the train station, especially with the crazy traffic here in China!

All taxis charge by the meter so chances are low you will get ripped off. You would need a Chinese address/name for every place you're going to as drivers don't speak English. A few drivers may want to charge more if there is high demand but they won't let you on before you agree.

Combining taxis and bus/metro would be most convenient. I usually look up wikitravel for each city I plan to visit to find the transportation options and tourist traps.