Heck even a typical FAU system will because they are in a basement/attic/etc..not to mention mini-splits....c) Roofs will certainly get more wear but are still expected to have a similar lifespan - with proper maintenance and especially with todays new roofing materials and techniques.You somehow forgot to count in your calculations how much an average landlord loses by having to deal with California's onerous regulations, fees, inability to evict, pay-to-move and related BS.... :-)

Medium size 3/2's rent much better than giant 4k sf mini-mansions2. 

One side has a new mini split other side still has portable AC unit. if they can provide proof of HUD voucher on each side being 1100 we will buy it.

I’ve seen the property and it’s in a good shape fully renovated one side has a mini spilt other has a Portable AC unit.

Depending on the SF, a small mini-split might be best.

Needless to say, I don't have much expercience in real estate, besides watching my dad build a mini empire of houses.

And Two: a system goes into play for each individual door....each unit is its own mini business (investment).

My idea is to do some construction and Re landscape the backyard, have the downstairs which we added bedrooms and a bathroom to upgraded, make some minor changes to the outside where we have a little mancave but my father put a bathroom in there as well and I was thinking to maybe make that a suite or its own mini apartment.

The 'Shared Practices' podcast is done by a guy who is in a military residency (right up your alley) and he has a mini-series with a guy named Justin Short, who was able to retire from dentistry at age 42 because of concurrent RE investing.

Mini splits are a common solution to cooling houses that don't have forced air systems - they are very efficient and give you the ability to cool specific rooms and zones individually.