[kijin]

a) This is why you go through the legal system instead of asking Google directly. Report malicious activity to a three-letter agency of your choice, and let them do the dirty work.

b) You can reduce the list of suspects significantly by correlating activity on multiple services from the same IP address around the same time.

c) You'd be wrong... especially since Google never really forgets who you are, even when you are not signed in.