Pipeline - Build form from Record, that only populates with fields that meet criteria?

I don't think so. A more normal way to do this would be to have the pipeline create child records as required. 

Another approach could have Form Rules expose additional field(s) based on the radio button answers. 

Mark, so what about a Pipeline that will copy only the fields of a record, that are answered 'No'? So say there are 100 questions, these random 18 questions were answered no, pipeline them to a separate table, where a Form can be generated for those questions?

I think you have two choices.

1. Use Show / Hide / Required from rules on the original form.
2. Have a Pipeline create a child table record for each "No" Question.  But the user interface will be more difficult to manage unless you are dealing with experienced internal users.

If you are worried about users changing their answer subsequent to when they initially fill out the form then you can use form rules to not allow that after a certain point in time. I'm not really seeing a point of basically duplicating your form and all of the questions into a secondary table. It just seems like double maintenance and double work and a complicated pipeline for no good reason.