Hi All!

I'm excited to be putting 20% down on my first off-market deal with a 30-year fixed @ 3.63%. It should cash flow nicely after renovations and hopefully I'll be able to cash out refi. I think I'm buying it well at a 22% discount (thats conservative) and there is value-add, but several big unknowns still remain. A downstairs apartment is not counted in the HLA and I can't tell if its ever been permitted. I'll need to pull permits and get it renovated before its livable. 

• Where do I start with that process of checking if its ever been permitted?
• How much does it cost to pull permits?
• Do I need separate permits for electrical work? Plumbing? Moving walls?
• How much of that work am I allowed to do myself, as long as its built to code? 
• How do I "turn it into a duplex". I mean how do I get it classified as a duplex?
• If it remains an SFR, how can I still rent out the two separate units without breaking any laws?
• A big plus is that I have the first option to buy the two adjoining lots and the lot that the house is on is deep and I could build a garage apartment. What is the first step of a new construction project? 
• How does one finance a new construction project?

Tons of varying questions and I really appreciate the input from all the great minds here!