Paul, Jim Walters Homes would do partial construction as well so the homeowner could finish it on their own. They did use subcontractors. They also offered a discount program where you and a neighbor could get a discount if you built at the same time.
Regarding the piers, back when your house was built Florida had a statewide coastal flooding standard. It had nothing to do with height and was based on the distance from shore. It's why many of the older condos/townhomes are up a level even in Blue Mountain Beach.
I thought I might be incorrect until you mentioned the A-frames and unfinished construction.
Here's some more info: