And offset the previous FHA loan payment showing that you're making the payments for it so it lowers his DTI.

Quote from @Brad Roche: The other thing that is great for the FHA 203K loan (not sure about the Homestyle loan) is that you can kick the payments out to 6 months of ownership (so close today and make your first payment July 12th 2025) if you are fixing up the home.

In this type of situation, they want low interest rate with low down payment also.

In this case, since they are borrowing their payments, these would get added to the principal balance each month, and interest would be calculated on that.If, for example, the interest rate on the note were 10%, they would implicitly be borrowing their payments at that rate.

Could you kindly suggest the best resources or methods to identify comparable properties in the area?

It isn't the metric you can talk about on a national scale, but if you keep buying the same product in the same area it is a very easy quick and dirty method to know how you are doing compared to other buys. 

Down PaymentSaving for your down payment is likely top of mind.

I am 21 with excellent credit and have enough/will have enough for the high down payment they require.

How will the partnership cash flow cover the HELOC payments if interest rates increase?

These are features like online renter payments, tenant portal (for payments and work orders), help keeping track of work orders, tax reporting features, and accounting functionality.