In this case the CA Residential Code says (R703.1.1) "The exterior wall envelope shall be designed and constructed in a manner that prevents the accumulation of water within the wall assembly by providing a water-resistant barrier behind the exterior veneer" (https://codes.iccsafe.org/public/document/details/toc/1005)This section means that as a designer (and contractor) we must ensure that the building envelope can resist water if the exterior cladding (rain-screen) is damaged.

If the tub is installed you will have to disconnect the tub shoe assembly and plug there. 

Assemble your team of professionals (Realtors, lenders, renovation guys) and trust their numbers. 

In this scenario, investors could also look to assemble adjacent properties during the hold period to further maximize the upside exit.

Will they have contractors they prefer to work with or will I have to assemble everyone and get the entire team on the same page?

Interest rates have been so low for so long, I don't even know if mortgages still assembled.

BGE has a "Legislative Liaison" who elevate complaints/concerns from members of the General Assembly - you probably won't be surprised at how much quickly your issue gets addressed when it comes from a politician whose job it is to regulate BGE.  

Do I approach turnkey providers or is there a way to learn about markets and assemble a team from a distance in these markets on my own?

@Travis HewlettIf you have a full apartment in the basement (with kitchen) then the basement ceiling / main floor assembly would/should be fire rated (1-2 layers of 5/8" Fire-X sheetrock).    

If your walls can be assemble by a machine offsite, it is going to require less work on-site.