There is simply way to many things that can go wrong building a new home with zero experience.

You simply have no credibility otherwise :) 

This is simply the reality of the paradigm we are living in today.

Every extortion attempt I have experienced in Baja has happened North of Ensenada.Beyond Ensenada are cool things like wineries (I do not drink wine), La Bufadora and its blow hole, great little fishing villages, Gurerro Negro and Scammons Lagoon (best whale watching on earth), San Pedro Martir (least visited forest region within a day of San Diego and has the twin Picacho del Diablo peaks and the national observatory), numerous Missions in various degrees of condition, hot springs, party towns (San Felipe), surf towns, snorkel/diving (anywhere in Sea of Cortex in Baja Sur), Sand Dunes (Baja races), etc.My worse theft south of Ensenada has been some bottled water.So the question is why Rosarito? 

Perhaps someone can tell me if it is alright to simply post here the contact info for George our consultant.

Ignore their attitude (yes it can be hard) and either start with an eviction as they are in violation of their lease for non-payment (the $900 they owe) or simply do not renew their lease. 

That said, it could be that the location of your property has some sort of local ordinance that has a 90-day limit, and Airbnb is simply following that.

Does anyone know if the fire sprinkler system will be needed if I simply rezone the basement as part of the first unit?

Yeah I understand how PMs work I'm simply saying suggesting hiring one to someone with 1Unit or even 10 seems silly.

Lots of great insight from the folks above.In my experience as an investor and multifamily lender in the twin cities, I would simply say there is no "right" answer.