It's a strategy allowing you to defer capital gains tax when you sell a property and reinvest the proceeds into another 'like-kind' property.

Even with $0 down I may be able to cover the mortgage with BAH from the military but then I'm concerned about all the other costs (CAPEX, PM costs, regular maintenance, taxes, etc.).

Landlord friendly, low taxes, job growth, and close to all the recreation of lake Tahoe. 

Borrow against them tax free if you need the cash.

Where does everyone find taxes, vacancy rates, expenses, etc.

I'd add to that--depending on what you do with the profit and how you handle any taxes.  

These lines of credit generally have 1-2 year renewal periods and require you to send the bank your tax returns and possibly personal financial statement on an annual basis.In my experience "HELOCs" are associated with your primary residence. 

When I do sell I do so with a Quit Claim deed for cash.

And does anyone know if there's any tax we would pay, since we're selling at a loss?

Recently listed one of my rental properties and had an inquiry from a company out of Philadelphia (Rental is in CT) who helps relocate people suffering from an insurance claim.