Zencart has the ability to separate customers into what it calls 'groups', and there are mods in the Plugins area that will allow you to assign pricing by group (which i assume is where you're headed).

As for the form, if you're really good with HTML forms and the code necessary to email the results, you could do it yourself, but I strongly recommend spending a few bucks on Machform. Either way, yes, it would go into an EZ page.