What specific page do I want to be on when I apply the add store cart details in database? (or do I need to create a page?)
What specific page do I want to be on when I apply/run Universal Email? (or do I need to create a page?)
I addressed these three question in my post above:
When you run the checkout wizard, the store cart details, store cart summary behaviors can be configured in the wizard. likewise, as long as you select to use a local checkout method, universal email will be configured in the checkout wizard.
These behaviors will automatically be added to the confirm page.
I pointed you to the tutorials because they address other points you mentioned, like wanting to offer digital downloads.