Purchase price: $275,000 Cash invested: $294,000 Sale price: $355,000 The property is a 2 bed 2 bath with a den and a 1 car garage.

You can find some 2 units under or around $250K but they have been sitting on the market for over 150 days which tells you its not a great deal if it were an investor woud have already purchased it 4 month ago.  

Purchase price: $15,000 Cash invested: $25,000 Sub to deal - paid the seller and wholesaler $15,000 + $7500 closing costs to assume $84,000 mortgage with a monthly PITI of $575.

My question is: After I build the units, can I do a cash-out refi and use the equity to purchase another home? 

If you're looking at a debt service loan, 15% is the minimum for a purchase but it's much more common (and rates are better) at 20-25%. 

I purchased a single family to rent out the rooms and it sent my finical plan completely off course because I was not as ready as I previously thought.

I just purchased my first duplex (only SFHs in my portfolio so far) and it doesn't have the gas/water split.

Recommend you first figure out the property Class you want to invest in, THEN figure out the corresponding location to invest in.Property Class will typically dictate the Class of tenant you get, which greatly IMPACTS rental income stability and property maintenance/damage by tenants.If you apply Class A assumptions to a Class B or C purchase, your expectations won’t be met and it may be a financial disaster.If you buy/renovate a property in Class D area to Class A standards, what quality of tenant will you get?

I have success in helping my out of states and foreign investors purchase properties with this type of loan.

Have you purchased any in the Clev markets as you said you wanted to months ago?