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.

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%? 

We believe that the roof will need to be replaced, but we haven't been inside yet, so rehab costs are hard to estimate accurately.2) What would you offer for the property if it's something you would consider?

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.  

The house doesn’t need much besides a roof, siding, paint, and some kitchen cabinets.

The house doesn’t need much besides a roof, siding, paint, and some kitchen cabinets.