I have been looking into several strategies to pay it off and one of my first cousins (who is an international student in the US) has saved up $15k and would like to partner with me/ lend me the money to buy the rental.My strategy was to use his money to pay off my 401k loan balance and then do the roll over into a self-directed IRA to buy the rental under my name so that he has the option to live in it (if it's a multi family) and rent the rest.I have done a great deal of research and it looks like as long as I don't live in the rental and also make sure that all the transactions are done within the IRA, then it should be straightforward. 

I'm looking at a property now that has been mis-managed by some adult siblings, who received the building after their parents' death several years ago.

Drafting and revising so many loi's, binding and non-binding loi's, poc's and several different other documents. 

Part of my contingency is seeing the rent roll over several years, and ensuring things are up to code.They haven’t explained why they can’t provide but the selling agent said they will have a hard time because it a mom and pop shop

I think this area is going to be attracting people and jobs for the next several decades.  

This is for architectural work only, and does not include the work of the other consultants (structural, mechanical, plumbing, electrical, etc.).So without having any other information but these several sentences from this architect, what is the best way to evaluate the offer from an architect?

You can use the loan for several things. 

Wendy is right - but there's a lot to consider when it come to fraud.There are several types of fraud - most have to do with intent and the actions taken prior to, during, and after the fraud takes place - and all can be argued one way or another.Pretty much every single purchase money loan has a due on sale clause - if you are maliciously trying to sell a property without paying off the loan, yes, that's Intentional Positive Fraud and you can get cracked on it pretty good. 

My research does not show a set pattern of acceptance of the last several months .

by looking up the lawyer @Craig Curelop recommended I located several real estate attorneys with ratings at avvo ( I don't recall the rules about posting links and such so you will have to use google to get there and select the real estate category)