It is absolutely vital I have AT LEAST first months rent to cover the majority of the mortgage while I fix up the other unit.

I would also add a 2% increase for expenses and rent year-over-year for a more accurate picture of future finances.

This will cover you shall any negligence occurs creating a loss for you.Installing cameras or having security is solely due to your discretion.

I am reading "Rich Dad's Real Estate Advantages" and the authors reference a $1:$9 accelerator to borrow 90% of cost of an investment and use your own money to cover the remaining 10%? 

I would start by watching their five part "Our Story" series, as it covers a lot of mistakes they made.https://www.youtube.com/watch?

-HOA fees are $160/month which covers everything exterior of the home (landscaping, insurance, etc).Goals-I completely understand that it won't cash flow, but my brother is pretty much a 2-4 year guaranteed renter of 1 room.

The best way to look at Holding Costs are those expenses that occur while it is vacant, but, would normally be covered by rental income.  

They have paid July rent already and I have 1 months deposit, which would cover the penalty.  

My concern is that the unit under eviction will be heavily damaged with no security deposit and insurance doesn't cover tenant damage, though a criminal act.

I personally go with very short term financing but the majority of my properties are paid off so in the event of vacancies, I don't necessarily have a mortgage to cover.