Go for 1) but don't use the users table but create a seperate table. Fill it up with as many columns you can think of are useful for storing user information.
Now you can either write up a small package to store the values in there, or create a predefined "database question" with "complex survey" for each of the values in the database and make a custom survey out of it, which has the benefit of being able to ask some people more questions than others and do branching (e.g. you can only show the IM contact information if the user answered to the question "Do you use instant messaging" with yes).
For obvious reasons you might want to add a link to the response of the survey for the user to edit on the /pvt/home page.
