Your options with out of the box progressive profiling in Marketo are to indicate what field you want to show, and how many fields you want to show per form submission.
So for your first form, you can specify for the form to show 5 fields, and as long as the person is not already in your DB or has not filled out a form, they will all be empty. For your second form, it will again show 5 fields, as well as any field you indicate to always show.
Here is a screenshot of your options when setting up your progressive profiling. I think with some custom javascript you can accomplish what you are looking for above, but not with out of the box Marketo.
Hope that helps!