Please I need advise on builders, cost, duration, financing and every detail possible!

Unless you are a builder and know what to look for.

I've tried looking for those myself, and the "safe" margin is 33% of ARV (in this case, acquire for roughly $500k)If the builder is aggressive, they could go for perhaps 40% but any higher and they risk losing money.If you have addresses, enter them into the County Map here and you can find the Last Sold price.https://gis.hennepin.us/Property/map/

I am renovating and selling the house and selling off the divided lot separately to a builder. 

Because of this, we know some of the ADU builders in town and can get you their info about ADUs.

Hypothetically, as a builder / developer, would you pay a slight premium for property that has the federal historic tax credit of 20%, a state historic tax credit of 25% and a city empty building tax credit of 25% - capped at $500,000, as well as a dense mixed use approved PUD, and a tentative $5 mil TIF district for the site?

You should have some of your portfolio in the public stock market, because it is a solid wealth builder over long periods of time.

A better strategy I have heard from folks is that the builder might buy you out of the contract at something like half of the full amount (difference between your purchase price and the market) to avoid having a new never lived in home on the market at less then their asking price for the same model. 

Can you get by with vinyl probably, as its used all the time in builder basic houses, but how well do they hold up to the hurricane forces I don't know.   

A friend of mine that’s a real estate broker and builder in houston Texas is in the Bay Area, downtown San Jose, California, to be specific for a few days and would like to connect with investors interested in investing in the Houston RE market.