Exchange 5.5 to Exchange 2000 upgrade

1) I would like to know how to upgrade my exchange 5.5 server running win nt4.0 to exchange 2000

2) How do i autogenerate user ids in windows 2000 server

3)In exchange 2000, how do i define e-mail address values by using variables so that the e-mail address would be different from the user id, i.e i want to achieve a different alias. What i want is the first letter of the first name+the last name. I can use the variable %g.%s@domainname, but that gives me firstname.lastname. Which variable can i use to achieve what i want