3. More broadly, you can take two views. One is that if an exchange has been hacked then that shows its security is poor and so it should never be trusted again. The other view is that a hacked exchange is likely to take every possible step to ensure that nothing like it ever happens again. I take the second view, but both views are legitimate
I would like to address this point of yours specifically
Theoretically, we can talk about these two approaches, though on a pure theoretical basis the first approach (i.e. never trusting a hacked exchange again) is certainly a preferable mode of action unless (and this is a crucial point here) you have additional info which could change your stance. In practice, the choice obviously depends on whether a hacked exchange did really improve their security policies, but without relevant knowledge staying away should be preferred. For example, Bter had been hacked twice within a year (or even within half a year), so trading there is likely an exercise in a sort of masochism
