However, by the time the appraisal is released the buyer is typically into the property for at least a few hundred dollars.  

Typical is $500-1000, but only if they close the deal.

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. 

Typically you'll need to make a larger down payment.

I have come slightly close to getting out all of my initial investment in the short term but I have not gotten out all of my investment (purchase + rehab) out due to 1) typically we do not get 80% LTV (we typically get 70% LTV) 2) the refi appraisals come in below market value (common issue in san Diego).Therefore I have yet to achieve the infinite return in the short term. 

The monthly savings typically outweigh the additional insurance cost.

The documentation that my lenders require are typically tax returns (last 2 years), rent roll of all properties, personal financial statement, and leases on the subject property. 

@Jessica Muto When we buy properties, they typically need a lot of work in order to get them for under market value.

Renovated the park thats about 3 blocks away, and a new shopping plaza is under construction about 4 blocks away is near 3 major freeways and the houses around are all typically rising to the 500,000 plus price range.

@Javier Arbelaez What you are describing is a typical C class property.