I am ready to hire the architect to begin the building design.

Hello Yucca folks, We are an architecture firm in the Hi Desert ie Joshua Tree and surrounding area, BennettBinns Architects.

I'm an architect in RI and MA, so take my advice with a grain of salt & then research your area.Zoning is LOCAL law that applies to property, it regulates the USE of the property (IE: single family, multi-family, commercial, etc) and the DIMENSIONS of the property (IE: how big does the property need to be for a particular use)Every scenario and property are different, but here's a couple of examples:An owner calls me.

If it is allowed you can try to connect with an architect and builder to see what can be built to maximize value and cost to see what type of revenue/profit you could expect.You could buy the lot, subdivide, and sell at a premium with preapproved build plans.Good luck!

My Architect say there is enough room to build 4 ADU on the lot.

So far, from what one architect/contractor told me, it may require building one unit at a time with separate permits.

there are probably guys that can put the property back together for $60k, but I would look at their scope and background very closely.I've seen dozens of guys get burned on gutted properties they think will cost $50-60k to get rent/sale ready...maybe this is who you want to flip your contract to...just watch the progress and be prepared to snap it back up when they run out of money.In reality, you should have an architect/engineer on the scene to develop the scope and construction cost estimate.

The husband is an architect (for the americans reading this the architect often doubles as your general contractor in South America) and the wife is a designer.  

2- how much should i expect to spend on permitting and architects?

So in a .75 zoning area, if you have a 6,000 square foot plot, you'd be able to have 4,500 square feel of floor area (the definition of "floor area" is a bit complex, but this will give you a rough number).If you need to go through zoning, you want to ask for the least number of variances possible -- FAR and density are pretty big ones to ask for.You should also engage with an architect.