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.

As long as it is allowed by law-I make no exceptions.

No matter the market conditions, there will ALWAYS be people trying to get into real estate by wholesaling...That said, if you stick with getting good at finding deals, it does not matter what you do with them, as long as you can find them.  

I haven't priced workers comp yet but I do know that in Oklahoma as long as it's a family business with less than five employees it isn't required.