As listed in the subject, I am from Maricopa, Arizona and I am beyond motivated to start getting involved in rentals and flipping homes.

I am looking at using flipping and BRRRR methods for my own personal REI.

I believe there’s much value to what you said, but it seems like it would mostly apply down the road when I’m able to more actively involve myself in more deals than just one.

I've held my license with HomeSmart, and they are great, just wondering if anyone would recommend a firm that's more involved in the investing world as opposed to retail. 

It doesn't necessarily not work, but you do have more pressure on your margins due to more people being involved making it that much more important to buy at a serious discount, and that is going to be your biggest challenge. 

My problem with the 3rd (and easiest for the landlord) method is that could end up being quite a few people who don't have a chance of qualifying that end up paying a non-refundable background check etc fee. 

Nope, for the most part you have to look through all the listings like everyone else, but many search methods will let you filter for short sales, and agents can filter for short sales, probate, REOs etc.

That would involve emotions and there is absolutely no place in business for emotions.

I have not consulted an attorney, it's a pretty simple transaction so I didn't think it would be necessary to get an attorney involved to draft an addendum.I'm curious if anyone has any experience in adding these types of contingencies to contracts that protect the buyer all the way up to the closing table?

Purchasing involves combing through perhaps hundreds of candidates over a period of months, creating a short list, visiting properties in person, bidding, hopefully winning one, then managing a rehab, and then interviewing property managers, and then hiring one.