1: If you used repair windows on the top, then you don't lose anything, else if you use fresh install windows, then you will lose all info. but if you fresh install windows and use different partition, then you still have all info. depend on what you did.
2: for firefox, you can download chiness verson firefox, then you can read whatever you want.
don't know if it is clear, if you have more question please feel free let me know.