I am not a contractor, but most bread and butter homes are pretty easy to estimate unless you get into structural or foundation issues.I have several great GC and handyman contacts as well as independents for cabinets, flooring, windows, roofs, paint etc if you plan to self manage the project.

And it's been the case, I have told him in multiple occasions, the floor is in good condition, even the kitchen cabinet is good, why is he trying to replace all these items and increase the work?

What I really need to understand, and feel like the final piece that is holding me back, is the costs of rehabbing; how much does it cost to redo a kitchen- counters, cabinets, flooring, etc.

What kind of cabinets should I invest in?

I'm looking for functionality and cost benefit with these cabinets.

A good contractor can give you an estimated cost of the major jobs like updating wiring, gutting a bathroom, updating kitchen cabinets, cost per sq.ft on carpet vs LVP, etc.

Each unit has separate utilities and electric.2 units with tenants get all new appliances, new kitchen cabinets/granite counters, new light fixtures and a 'light' bathroom update (resurface tubs, update vanity and light). 2 units that were vacated were completely gutted and redone, including the above mentioned and new shower/tub inserts and plumbing. 

Originally we were going to keep the cabinets  and install new doors but after finding they were the old particleboard we decided to scrap them and go with new.

Once the legalities are straightened out, a nice way to dispose of their items is to contact your local Habitat for Humanity and ask if they have a ReStore.I'm on the Board of Directors for the Habitat here in Waterville, Maine and our ReStore is a significant contributor to our funds - and that helps us to build more homes.ReStore accepts donations of all sorts of household items from furniture to tools to sets of dishes to cabinets and plumbing fixtures. 

Concrete countertops, new sink and faucet, new durable floors, tile backsplash, refinished and painted cabinets, added dishwasher, etc.