These repairs I speak of were all done 'in house' by the PMC so no payment was made to an outside company.

They are asking for 20% down and a 3 year balloon payment.

Otherwise as I understand it you should be filing quarterly estimates and payments.

(Loan balance: $190,000 + $50,000 arrears + $10,000 assignment fee = $250,000.)Sub to deal. existing rate: 4.75%Mortgage payment is $1,450 and rental comps are going for about $2,450.

The main method that most of us use to become more profitable in this space of investing is securing private financing.  

On the other hand, Conventional loans require higher down payments. 

Whether you prefer to read hard copies or listen to audio books(my preferred method), here are a couple on the topic of Wholesaling.The Ultimate Guide to Wholesaling Real EstateThe Beginner's Guide to Wholesaling Real EstateBigger pockets also has a book on the Subject How to Wholesale Real EstateHope this Helps and gives you somewhere to start.

Using the Gross Rent Multiplier appraisal method, the property was appraised at $400,000, and I successfully sold it just below this price within a few weeks of the appraisal.

With such a high DSCR what kind of interest rate and/or down payment should I expect?

After a series of excuses and delays, they are saying their bank transfer is coming through Monday and can send me payment then.