Generating Page Via Plugin

I am writing a plugin that takes in data from the user via a widget that contains drop-down lists. Once the user selects an option on each of the drop-down lists and hits “Place Order” the plugin needs to direct the user to an “Orders” page where all of the data they selected in the widget is carried, or POSTed, over to the generated page where they can review the details. I have already created a custom post type for “Orders” and for the products being ordered, but I am unsure of how to accomplish the page generation.

Should the page be created as an empty shell/holder(and appear in the admin dash), and then be populated via PHP in the plugin or should the entire page be generated via the plugin(not appear in the admin dash)? Either way, what is the best way to accomplish this?