Have you updated to the latest version of iTunes? This can be downloaded here if you haven't already. You may find that you're receiving errors because Apple's servers are taking a hammering right now from people across the world all wanting to update their devices as well.
You know, I cant really answer that. The 3GS I am usnig as been dropped about 100 times. My daughter and my brother-in-law have both owned it and now me. The only reason I have it is because I handed down my iPhone 4 to my daughter while I wait for the 4S. Its not in the best of condition. It lags a little but it was like that before iOS5.