What am I missing if I purchase, improve and refinance using commercial lending?

Is there any harm (mainly tax liability) in waiting 3.5 years and both refinance the mortgage and transfer the title together? 

Does this affect a cash-out refinance or pulling out equity in the form of a HELOC/equity loan?

Purchased a $535k duplex at 7.125% & have the opportunity to refinance to $548k at 5.75%.

If I do a cash out refinance and assuming I get a loan rate of 7.5% that would put my monthly payment up to $1800.

I would say Corby makes a really good point with regards to the MI that you pay with FHA. 1) I definitely would refinance into conventional (if that is an option). 

How would you structure a deal so that the private money could cover the down payment and fund the rehab in order to minimize money out of your pocket and being able to pay the private lender off when you refinance? 

Maybe refinance in a few years and buy your first investment using the money you’re going to get out of refinancing?

Since we won't have a mortgage, our hope is the property will appreciate over a few years and when (hopefully soon) mortgage rates come down, we can do a cash-out refinance on the home and invest in additional property(ies).Does this seem sound?

I hope the first lender can will agree to refinance the loan and I will carry the loan and pay monthly.