Group Fields into Fieldsets, also text and headings in survey

I'd like to have another tab, which would allow me to define fieldsets. Once fieldsets were established for a form, I would then be able to assign assign elements to that fieldset.

A feature that would work with this would be the ability to add instructions into the form interspersed among the fields. I could see being able to designate either text or headings, I suppose it might make sense to have a single type (i.e. read-only), and then be able to designated the structural weight (p,h1,h2,etc.).