If you are the shortstack when the deal is done, always remember that you should get more than the "pure" mathematical value of your chips. On the other hand if you are the chipleader you should be prepared to accept slightly less than the "pure" mathematical value. This is because I believe that there are some implied values that need taking into account.
IMHO of course.
You're right. In a tournament with more than one prize, each chip you win is worth slightly less than the chips you already have.