What permitting agencies will we need to consult? 

By answering that question you created agency with that seller. 

I would recommend a contractor that is credentialed in fire restoration (IICRC is the agency that provides such credentials).

I'm quite experienced in real estate agency and sales, deal analysis, and coming up with creative solutions to property rehabbing.Happy Real Estating!

i had bought a sonos playbar and sonos 1 dual speaker system but after reading more about the sonos system with respect to a multi user platform i am not really sure its the best choice.first item that is a of a hassle is the need of the sonos app. 

Yes I do run a digital marketing agency for Real Estate investors... but I actually found this deal by cold calling, lol so it is definitely not a way for me to advertise my Digital Marketing.

I've had about 7 years of good experience a Shelter Insurance agency. 

(e) (1) Notwithstanding subdivisions (a) to (d), inclusive, a local agency shall ministerially approve an application for a building permit within a residential or mixed-use zone to create any of the following:(A) One accessory dwelling unit or junior accessory dwelling unit per lot with a proposed or existing single-family dwelling if all of the following apply:(i) The accessory dwelling unit or junior accessory dwelling unit is within the proposed space of a single-family dwelling or existing space of a single-family dwelling or accessory structure and may include an expansion of not more than 150 square feet beyond the same physical dimensions as the existing accessory structure.

Contact your local tenant rights agencies for help with negotiating with the landlord about getting your funds back. 

Getting your primary house & house-hacking (or adding an ADU to it) will help with your dual-goal of owning a primary residence (and benefitting from MID) & generating income from it (partially offset by depreciation).