To what indices do you tie your floating rate mortgages? 

I think I'm drifting more and more into his camp.

GSEs offer very attractive terms for multifamily properties nationwide, including various fixed and floating rate loan terms, early rate-lock options, and future supplemental loans.

I'm not a lender and others can chime in....there are lenders floating around on the site.  

Your current deal might, if you can float the below market unit until the lease runs out, plus you will be out of pocket for the repairs.  

ie. income is greater than all your expenses(this includes debt servicing also).then i think you are ok to borrow from one to "temporary" keep a float the other.

Although acquisition prices have generally gone up, there are always decent cash flow positive deals floating around.

The process can be very painful, as I entwined before, I only speak of my immediate experiences with these, my experience to date has been frustrating and because I am not under a timeline I am ok, with these short-sales floating around for 10-14 months, but in your case I do not think you can do that.  

You get a lower fixed rate vs the Higher floating rate on HELOC.

You can find some pretty solid numbers floating around.