Let's also say together we purchase a multifamily @ $1,000,000   I understand the prohibited parties issue.1) If we (myself and the SDIRA) were going to put 20% down...does that have to be in equal amounts meaning 10% from me and 10% from SDIRA and everything is split 50 / 50 or can you still have normal deal partnership flexibility...so something like the SDIRA puts in the entire 20%, owns 50% of the property but gets a "preferred return", etc.2) Perhaps the bigger question is financing, I know there is SDIRA financing that is non recourse but that is typically for 50% LTC. 

In a perfect world: (in no particular order): Square/rectangular shape, 1-story, open floor plan, lower pitched roof fully trussed, slab on grade monolithic foundation, 24 o.c framing everywhere, T1-11 plyw. siding, minimal windows, minimal doors, minimal trim, minimum code electrical/HVAC/plumbing, carpet everywhere, avoid tile, laminate countertops, Home Depot cabinets, basic fixtures and appliances, no fencing, no trees or old stumps, minimize landscaping, minimize driveways and walkways, forget pavers, cleared flat lot, no fill, utility hookups available in front of house and best case they are aleady tapped, inspectors are easy to work with and pass everything the 1st time, subs show up when they need to and actually care.

I told him I'd send the title company a huge wire of non refundable EM if he let me be a backup at my price in case his buyer flaked. 

Additionally, I'm not certain but I believe that every penny of withdrawal taken out of a (non-Roth) 401k/IRA during retirement is taxed at your ordinary rate, which is likely to be higher than tax preferred treatment of real estate.

Can anyone recommend any particular way to negotiate rates, and if anybody knows what the current market rate is for interest rates these days on REFI'S. 

Most likely the co-op is non-warrantable, meaning Fannie will not lend there or waive the building.

Any particular justification as to why North of Arlington is a better choice?

Hey guys, im a new motivated investor,i am 20 year old and im looking to buy a rental property in the future but where i live 90% of the rentals do not cash flow and if they do, they are D class property or non-legal/non-conforming duplex/triplex. 

You need to have a good agreement vetted by an experienced professional.If one partner puts in more money than the other, you could change ownership interests, you could treat it as a loan, you could reduce income/profits from the non-contributing partner until the contributing partner is paid, etc.You will want to discuss with each other who will be doing what management functions and whether that is worth anything to you both. 

But usually it's unseasoned nature is a non starter and requires too much of a discount.Either a partial exchange (opt 1) or a note buy out (opt 2) will work for you quite nicely.