If a dynamic IP is giving you headaches check this out:
http://support.dyndns.org/dyndns/
Otherwise your (max client rate * # of players) will give you how much bandwidth is needed to run the server. If you are on a cable connection your dreams of a 32 man server are not going to come true. Cable just can't handle that, you will problably have horrible pkt loss and ping spikes from hell. I would start by setting up a 8 man server and tweaking it. Play around and test values with your cable friends and find what value works the best. GL on your server bud.