Maybe figure out what you “need” to live on (I have a pretty liberal definition of need: loans/taxes/food/insurance/housing/internet/phones/etc. ) and how much of a safety margin you have on top of that. 

Arm yourself with a realtor who specializes in investor clients.

I don't think they even care what you do (generally speaking, underwriting standards may prohibit them from lending to someone who's an illegal arms merchant, etc.).

If you can secure that my suggestion is go for a 30 year fixed rate, which is cheaper than any available ARM at the moment.

I found a local bank that did a 5/1 ARM at 80% LTV, so I took that and will keep looking for a 15yr or 30yr fixe rate mortgage.

(FHA, VA, Conventional) (FHA you need 3.5% down, VA thats used for people who are serving or have served in the Armed services, and Conventional you need 20% down) Do you have any capital to get started? 

The key is that you let them know that you are willing to meet them halfway so that they can be satisfied with the safety and integrity of the structure but that you are also not working on an unlimited budget.

which has a property management arm.   

As I understand it, the HELOC is an ARM but it comes with no fees/closing costs, etc.

You'll certainly want to replace the wiring, not only from a safety standpoint but also many insurance companies won't touch it without rewiring.