1. You need to create your own account on that machine and another for the "bunch of people" who are always using it. your screen saver should require a password to unlock it. Require them to log onto the machine as "limited users" and then they don't get to see your stuff.
Alternatively, you could put your stuff in the File Vault which is basically a directory that requires a password to open it. Be careful here though. Forget this password and even SJ will not be able to get your stuff.
2. Yes, this is a function of Word and details of how to do it can be found in the Word help files
3. See answer #1

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