Using forms or other means to track user activity and plan m

Hello,
A multi-part question from a newbie evaluating 4.4... I apologize in advance for this being a bit convoluted.

I am interested in tracking logged on user activity so we can use it gage customer interest and also use it to trigger other marketing events. For example, if someone downloads a price list we want to notify Sales so they can call to offer a quote. I am contemplating doing this with very short forms but would like to know if there is a better way? 

Is there any way to pass logged on username to Google analytics and use their engine to track the visitor’s path through the site?

If we use short forms and a user is already logged it seems silly to make them enter their username on the form. How do I pass their username to a form?

Eventually I want this to grow into full blown drip marketing, where a form submission or link clicked in an email could add a user to a number of (mailing) lists or change database fields.

Google Analytics accepts custom variables:  http://code.google.com/apis/analytics/docs/tracking/gaTrackingCustomVariables.html