Basically you are only paying for the land and the pleasure to remove a whole lot of garbage. The buildings have a negative value. I have no idea how much it would cost to erect a home, garage and office space but likely it isn't cheap. And it looks like the zoning designation doesn't allow commercial activities.
Just install bathroom and kitchen in the existing space and job done. Got to remember, this is the kind of space Fran is looking for, a big industrial type live/work space.
She doesn't need a home and has specifically said she wants a large live/work creative space.
What she does it hardly "commercial activities" and would be easily allowed in any existing home or gargage.
Doing construction work is not for everyone. You'd need the skills / experience, tools and to be able to work fulltime on such a project for weeks in order to make decent progress. I've seen various people take on construction projects that turned out to be way over their head. It is not as simple as they show on TV.
See Fran's latest video, she shows photos of construction work she has done on other places she has rented. Complete fitout of an empty space.