DSCR loans are based off of down payment, credit score and either actual or market rents so it helps to supercharge an investor's real estate goals and net worth.

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

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

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

(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.

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.

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

When you're about half way towards saving enough for a down payment, reach out to a lender to have them assist you with getting your ducks in a row.