Dennis @ PerfectForms
It sounds like you have at least 3 stages: New (when it opens, grabs the custom parameters and closes), stage 2 when the user accesses it via the link, and stage 3 (closed). You should make the last stage a closed stage. If this is a long survey, you may also want to give your user the option of saving and returning later which would involve more stages.
I cannot diagnose why your notifications are not sending without seeing the .pf file for your form.
With regard to mandatory fields I find best practice to be using a check mandatory behavior object rather than the mandatory check box for each object on the page. Instead of using a submit button (or a page button) use a regular button and change the caption to next or submit. On “button is pressed” use a check mandatory object and then submit or show next page. This way your form can submit under one behavior without concern form mandatory objects in another behavior. The other advantage is that on a multiple page form, your users will not get to the end before finding out that they missed fields way back on page 1.