I do have plenty of cash reserves at the moment, however I still dont want to spend all of them on only 6 units.I am thinking I should get a quote from a licensed contractor to see what things are at worst, then have my own handyman do all he can do on his own, then maybe get some plumbing and electrical quotes from licensed individuals, and then let a contractor handle the rest if I feel overwhelmed. 

My suggestion:1. don't use % for capex or repairs, do the calculation from fundamentals (cost of roof replacement, plumbing replacement, flooring) divide by average life expectancy of those parts.

This includes insulation, roof, siding, frame, electrical, plumbing, windows, stair sets (1st floor to 2nd floor), light fixtures, kitchen cabinets, bathroom toilets, vanities, shower/tub, panel boxes (delivered not installed), sheet rocked and primed, transportation and setting of the boxes. 

BUILT 1964 during a drought so city put a limit on plumbing.

In the engineering department, I probably want to have experts in electric traits, plumbing, heating and air conditioning, flooring, etc.

I completely rehabbed the systems of this property with new electrical and plumbing systems.

You may want to check with your bldg inspector as some will allow the owner to do a lot of the rehab as long as you get the required permits.As mentioned above the HVAC, gas lines (& bonding if CSST is used), plumbing, electrical service panel &/or sub-panel wiring needs to be inspected as well as the required GFI's etc.

(electrical, plumbing, painting, adding two bedrooms, etc) Also added a privacy fence and a deck.

All new HVAC, insulation, electrical and plumbing including gas and sewer.

LED lighting, new electrical panel, new plumbing, new central heating and A/C for maximum safety, comfort, and efficiency.