I am hopeful I could under bid and get it at a good deal.I would like to put an offer in, but I don't have enough cash to pay the full amount at auction.

He says if I pay him full asking, he would provide me with the 20% down payment since we could avoid realtor fees, and make up the rest by paying full asking (he had it appraised), rather than accepting an offer under asking.

I've been in real estate since 2015 and currently offer accounting services to investors.

There's nothing better than getting an FHA or conventional offer accepted by an unsuspecting seller, knowing you will have plenty of opportunity to re negotiate once the appraisal comes back.

Seller is an idiot for even accepting your offer.

Basically, if you are committed to this investment thing, you will need to make some uncomfortable/hard choices to eliminate the credit card debt and lower your monthly debt.Once that goal is complete, you can begin practicing habits to live below your means and start building up your savings. 

Happy to offer up some more insights if you're interested.

Admittedly I am new to this and I haven't written a creative offer before. 

For example, can I simply let a friend borrow $25k & get paid back with some interest or is there some reporting & rules involved before engaging in such practices?

Focus on how to juice cash flow if possible (rent by the room, separating spaces, etc.) or decreasing expenses (assuming a loan, looking at new build incentives, aggressive offers w/ rate buy downs that work for you, etc.)