I'm new the the BiggerPockets ecosystem, if I were to explore that route, what's the best way to look for such a parter? 

Manage basic financial structures, possibly even waterfalls and distributions.Some form of onboarding new investors will be helpful and the software I have explored all tend to have a little something.

When I'm not being Army or working my W2, I'm exploring nature.

You will be able to get situated and explore the city and the different multifamily markets.

I think that is going to be my best move, although I am still exploring the best option for this first venture.

You're welcome to call me to explore options.

No matter what you do, good luck and keep exploring.

I am exploring ways in which to assist them. 

I told him that I won't be paying it as he didn't explore all options before passing me on, so we might have been able to work together and then there wouldn't be an invoice for $4,500.

If you're doing these things then you might find solid property liability insurance with a back up of umbrella insurance (as needed) far more than adequate as I have found over the last 20+ years.If in contrast you want to run a loose and fast rental property operation letting any Tom, Dick or Harry manage or lease your properties then maybe you need to explore those other options.