I’ve dealt with home inspectors, contractors, problem properties, condemnation notices etc and have worked along side architects and engineers.

AND Architect.

Thanks for the comment, @Greg Dickerson.I haven't hired yet an architect for producing a complete set of architectural drawings, but I am targeting something like this nearby property in terms of type, style, and finish.I will reach out to a few local contractors for getting a more detailed construction cost estimate.Is there there a rule of thumb for estimating operating expenses?

@Pedro SenaI have someone but it depends on the work you need to be done - plans, drawings, architect filing with Building Dept., contractors, etc.Alex Jerez - BuildSprout is who I recommend.

Are there any quick, simple and free softwares out there to develop general basic floor plans?   I have Adobe Illustrator & Indesign, Im a graphic designer now of 16 yrs... but using those programs for floor plans...

If that "use" is allowed, then it is a matter of finding an Architect and Contractor to start the process.

Should you want it to be a legal two family you would need to go through the variance process and get an attorney and architect involved.

We're in touch with an architect who has worked on at least one fast remodel.

We're in touch with an architect who has worked on at least one fast remodel.

And at that point you might as well have started from scratch with an architect.