Based upon this I would look at an actual dollar amount, not percentage that: 1) enables you to live in a safe neighborhood and decent schools district, is modest in size and fixtures, and has payments sufficiently small that you are still able to invest at least 10-20% (or whatever your target is) of your income. 

My guess is your original contract with the seller is not sufficient.

As far as sleeping arrangements go,  Lots of places have a futon in the livingroom or a couch that turns into a bed so they can sleep 2 more people.  

He agreed to join in investing with me and work for me for no costs at the start of our business (all income would be going back into the business until it's financially self-sufficient)On top of that HUGE benefit seeing as contractors absolutely drain cash during a rehab, my dad told me that he will possibly help financially support me in the start of my business.

I say make an offer you won’t lose sleep on.

I like to sleep at night. 

For example, if you can prevent the nightmare tenant, you avoid--well-- nightmares (like real ones, where you lose sleep or wake up worried how the eviction will play out or toss and turn wondering if the non-paying tenants are trashing your place; you drift off imagining them doing nefarious things under dim lamps with bunson burners and beakers amid a pile of trash surrounded by half feral pit bulls resting on dirty mattresses)... 

I am primarily wondering how to best determine whether a particular single/multi family home would be a good candidate for being self-sufficient each month (outside of unforeseen maintenance & repairs) based on what rent is collected.

Thank you so much for your time and input, I have a while before I can take action on anything, but I want to be able to analyze a deal in my sleep by the time I get there and be confident that I did it correctly. 

You may want to sleep there or use dry gas to attract them...CO2 is what they track.