All expenses are paid by the IRA, all income flows to the IRA, and you cannot inject value into the IRA by giving the IRA free labor.With the ROBS program, you can use existing retirement funds to capitalize a business, but the business will be a taxable C-Corp.  

Economically it would bring in another stream of revenue for the city/towns and allow its citizens to get to Boston area jobs where wages are higher and bring it back to that community to inject economic spending. 

Maybe a cap rate would help you if you are trying to decide which one to buy: an injection molding company in China, or an apartment block in the Baltics, of a sprocket dealership in Texas.

You can direct the affairs of the LLC, but may not benefit personally through doing so (other than growing the value of your IRA, of course) nor may you inject value into the IRA through the provision of goods or services.There is no black and white rule as to when an IRA crosses the line from passive investing to "engaging in a trade or business on a regular or repeated basis". 

Does the existing building need an injection of capital to complete rehab, and thus boost NOI? 

My only mistake is that I’ve used one in the past to help the business when it has some issues that required a cash injection. 

Sometimes it’s epoxy injected repair which could have been done by the previous owner.  

Financially, we have about 40k pooled in our fund now, and inject about 15k each year (before any gains/losses).  

If the LLC has no money to pay for the defense, you'll be injecting money into the LLC yourself to cover the legal fees, just as if you had no LLC at all. 

The likelihood that you could buy out the investors from refinance proceeds alone isn’t likely to work mathematically unless you inject a lot of your own capital.