I help work on the properties myself, and have found great sub contractors for great prices as long as you put out referrals and keep using Them they are always at your mercy( and helping you save on repair costs). 

I am confident I can walk down any street in Columbus without getting shot as long as I am not trying to rip off drug dealers. 

AirBnb is an option as long as the unit is furnished nicely and all the towels, sheets, kitchen ware available.

You can definitely use conventional financing as long as the deal and numbers support it.Most people buy cash with BRRRR due to the condition of the properties, time needed to close, etc.Another reason is to avoid 2 sets of closing costs on both the purchase and the refinance.

Has anyone gone through this process before and may be able to lend some advice on how long a process like this can take?

As long as you are setting value in your place, you will be fine. 

You pay a little higher rate and maybe a point or two, plus maybe an extra junk fee - but there should be no limit on the number of loans (as long as the property generates the needed cash-flow to cover).

my thoughts are that as long as you have the cash or can get financing to fund the soft costs and hard construction costs then i think you would turn a profit. as you said, your betting on avg house cost, hopefully you've done due diligence to check that but ultimately if that area is in a housing shortage then I think the market will eventually meet or exceed 

The amount of equity you have shouldn't really matter as long as you have a positive cash flow.. 

There are no penalties as long as you do this before the tax filing deadline.