Disqualified parties include you, spouse, lineal family and entities like businesses or trusts controlled by you or lineal family.As such, your wife's management company cannot function as a vendor to your plan.As the plan trustee, you (and your wife) are allowed to administer the investments of the plan.  

Sure, a bit:  Deserving applicants can be referred to the Middlesex County Board of Social Services  (website below:) https://middlesexsocialservices.com/programs/and they administer temporary housing assistance, long term housing assistance (section 8), emergency relocation (think domestic abuse victims, flood victims, etc.) and other programs. 

Section 8 is a federal program but administered locally, so maybe things are different in your neck of the woods but I doubt it. 

(see http://www.biggerpockets.com/files/user/wakeProperties/file/wells-fargo-business-deposit-card-agreement for how we administer it...)

The old 401k is administered by one of the brokerages, and I thought it might be easier/quicker to open the checking account at the same place.

I would definitely use an IRA LLC (checkbook control) or a self-administered solo 401(k), if you qualify.  

Now, what is unusual that no one here has experienced is the fact that a third party servicer has gotten involved presenting the contracts being administered.

You then vest title to property in the name of the LLC and can self-administer the property such as paying the bills and collecting the rents - with all of that activity flowing through the LLC accouint.There is also a similar program known as a Solo 401k that is available for folks who are self-employed and have no employees.Regardless of the structure, there is limited oversight over each and every in/out of funds.  

Section 8 is administered locally so the administration of the programs vary around the country or even state.

My biggest concern is my ability to administer the loan properly.