Is the interface for setting up teams - the "Team Wizard" - available yet? I can't find it.

If I make a personal submission now, does that affect my ability to form a team later? If not, my team-mates and I would be better off working individually, since we can make more submissions that way.

@mkwan, you fill in the team wizard when you make your first entry. Team mergers will be granted at the organizer's discretion.

I can't figure out how to add a member to my team using the team wizard (and I've already made a submission). Do I need to contact Kaggle directly to make it happen?

Since you've already made a submission, use the "Contact Us" link at the bottom of the page and ask for a team merger with the details of who you'd like to add and we'll get things sorted out.