I come from a blue-collar family whose patriarch was often unemployed due to multiple factory shut-downs so the only money advice I was ever given was to get a good office job and invest in my 401k. 

When we purchased the land for our new builds, we were advised that the office and structure was considered a tear down.

The SELLER or current owner of the home who could not use a realtor, has absolutely no knowledge, skill, or understanding of the process of selling a house seems disturbed by me earning to much of a profit.The paperwork is at the lawyers office for pre-foreclosure to begin.

I tried calling the tax office of the county but the individual who answered the phone didn't seem to know and transferred me to a supervisor, for whom I left a VM but hadn't heard back yet.Thanks!

Maybe not always in your office.   

I'm keeping a Pittsburgh based return address on the postcards/letters, but I'd rather not have a giant collection of returned mailpieces pile up for me to collect on a regular basis.I've heard of an option where the post office can send you photos of your undeliverable mail and then discard it for you, but I can't seem to find anything about this service on the USPS site.

I do not need any support in the way of marketing, office or other overhead.

For example, could I sell a 5 million dollar office building and go buy a 10 million dollar portfolio of 100 SFHs that are individually deeded?

A parcel split in Florida typically involves filing a parcel split request form with the county property appraiser's office, and before you file it, you get the survey work done and find out if the relevant building or development department will support your request or not.

I have moved to the new home and work remote but plan to work from our office in San Francisco after remote.