If your encrypted passwd after you change it back looks different from what it looked like originally, do not worry. Send the line with the username and encrypted password to the Mercury team, who will install it for you. Also, tell us what domain you're going to be accessing the repository from, so we can adjust our security setup to allow you access. If you don't say, we'll assume it is the same as your email address. Access via Windows works just fine.
Most firewalls are setup to allow CVS access through.
There are some checks that are done via questions. CVS should compress most of this stuff while sending it. This is a forum to ask questions about how to change something, discuss design trade-offs, and report on any development that you suspect will influence others. Before committing any code, read the policy on reviews for the Mercury system. Basically, we don't commit broken code into the repository, and we don't commit un-reviewed code.