Hard money is a pretty common loan type for BRRRs or flips, it is handy to start. 

the storage thing is pretty common, seen several grocery stores turned into that. 

I don’t know how common vacancies are but I would say I could cover about 4-6 month in case of an emergency  

Quote from @Ed Daniels: Very common to overthink this investment.  

This is one of the most common challenges in the LA County community on BP.

They are far more common now and harder to find models without but:1) these add cost to the purchase price2) they don't bring a lot of value3) they can leak or detach and damage the propertyI own around 50 doors and I cap off the line at the wall or in the basement with a valve and a cap so the potential for leaks is 0.00001% :-) 

Even at 30% discount, the QBO Plus subscription most Real Estate investors have to have is still $63+Tax.You may look at Xero, I heard they have the Class feature but it is cheaper, it's just not as commonly used as QuickBooks.

If anything, have a small sign in front of the house that says who the builder is and phone number (that's common for contractors to do, and also so that neighbors feel they have some to call if there is dust blowing from the site or whatever), and then you may have people calling you asking about availability (people always want something more that they had to chase and can tell their friends the story of how they got the house). 

I will plan to improve the common areas, property fencing and siding. 3 of the 4 units have been turned in the past few years so there is not too much to do inside.

That means having procedure and protocol for every situation--or at least, every common situation.