I have never purchased a home before so I am wondering if the conventional mortgage preapproval process is similar to an IRS audit. 

The cash flow can help from a DTI perspective if you’re going the conventional route but no bank is going to give you the income approach to valuation on a duplex.Did you have a realtor run comps and give you an ARV?

Time isn't the big thing, I forget why flips don't work but I think it has to do w/ them counted as inventory.

@Kenneth Stump Duplexes can qualify for FHA, VA, or conventional financing if you plan to live in it.

If i move out after a year, do i have to cover whatever the difference is from the 3.5% to the usual 20% or so of a conventional loan?

We bought our first house last year on a 3% down conventional loan.

The inventory of SFR is extremely low and prices are at all time record highs.

But, at this point, give my non-conventional financial situation, is it even worth trying to "fix" my dti?

We make this process simple by provding the inventory, education and financing so you can easily acheive these results.

I utilized conventional financing at 20% down to avoid PMI, so it ate a lot of my savings.