MDF, particle board or plywood?  

No, as it seems to be "dust particles/control on wood surfaces".  

I would 100% go with hardwood cabinets over particle board.

Prime with Pro block oil in gallons or aerosol cans depending how bad it is and top coat with any latex paint.

Because it was more of a commercial building before, all the ductwork is in the ceiling, the ceilings are the typical florescent lights and particle-board-ish squares you see in offices, and the bathrooms are small with those classic tiny, heavy white sinks with ugly faucets that you find in other commercial buildings (where you can see the metal piping underneath)Has anyone tried to renovate a building like this?

Yours is a question about MF valuations, not the Large Hadron Collider and theoretical particle physics.

Cheap carpet, cheap "hardwoods", particle board cabinets, crappy moldings hollow doors, cheap door knobs that jiggle and don't feel solid, etc etc.

Real Formica(tm) on plywood substrate is what you see serviceable in those 40 year old kitchens, not the home center thin laminate on particle board, which inevitably gets wet and self destructs.

I believe in doing things right and wanting to make a place my tenants can call home so out came the layers of particle board, drywall, and then plaster and lath.

DO NOT try to remove it yourself, it is against the law for one, can extremely dangerous for second, and you could invite a wonderful EPA fine and lawsuits by the neighbors that you expose to airborne particles.