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%. 

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

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.

The property is being purchased at 103 with an ARV of 375.

Quote from @Enrique Toledo: I came across a really good seller financing deal and I would like to purchase it as my first deal but I don’t have enough money for the down payment.can I use a lender of some sort to give me money for the down payment?

I invest in an A/B area with an average purchase price of $500k.  

I even purchased his cash flow board game to play with my family.