It all comes down to what your comfort level is. 

I am curious if there is a negotiation course out there for landlords to sharpen their skills.

I am in the camp that anyone can be found rather easily but it's a choice of your comfort level and what your desired outcome is.  

We know nothing of your skill set, resources, or abilities.  

Or do you use it to make high-level analysis of property values? 

LCC as a basic pass through and limited partnerships depending on equity arrangements and profit share of the parties add that extra level of flexibility and not needing to split potential individual partner costs or liabilities.  

With skills like yours you should get connected to a REIA in your area and find someone to work with.  

What is your secret sauce or what skills do you have in your toolbox that help you acquire these properties at discounts? 

Early investing builds equity, generates income, and teaches property management skills, but may strain finances.

At a high level based on what I'm reading, this may be one of those where you give your brother an ultimatum: work together as originally discussed, or you buy him out and call it a day.