"Ignorance is bliss.

This tenant has ignored my warnings - to stop smoking in the unit (multiple times), having unauthorized guests in the unit without my permission, have spread rumors and lies about me throughout the neighborhood, and have ignored my texts (only method of communication).  

There would also be a mismatch at the state level depending on which state you're looking at since some conform to the federal rules, some have their own, and some ignore it entirely.

Don't ignore those vibes.

I would argue that just because they "may " be ignorant of the rules doesn't mean they are not trespassers.

Consider it a blessing that she flaked and kept ignoring your original offer- Dodge the bullet NOW....DO NOT RENEW HER UNLESS SHE PAYS AT LEAST CLOSER TO MARKET RENT..... if you think your unit doesn't really meet market standards to get market rent, then at least get it closer or at minimum keep it "as is"...

When in fact, syndicators have to comply with federal laws about money raising, and generally the persepectus/info sheets and syndicator's history are quite useful in evaluating deals.To the OP - ignore the suggestion of finding syndication deals. 

Please excuse my ignorance. 1) In an attempt to learn from folks who have done this, what is the best way to finance the gut rehab of the existing property and the new construction of a duplex?

Crazy but there are a lot of tenants who are ignorant to the consequences who may vote for this.  

Forgive my ignorance.