So I have a rental property with two fairly mature trees directly in front of it. 

Seems like this property is not really cash flowing on year 1 or 2 but there is a good potential for appreciation if I buy and hold.

Given your strong net worth and experience, investors might be interested in a short-term investment with a clear exit strategy.Home Equity Line of Credit (HELOC): If you have significant equity in your personal residence or other properties, a HELOC can provide access to funds without selling any assets.Securities-Backed Line of Credit (SBLOC): If you have an investment portfolio, you could borrow against the value of your securities without liquidating them.Seller Financing: Negotiating with the seller to finance part of the purchase price can reduce the immediate cash requirement.

And as you seem to have done your diligence on that one property, so have we.

He made a little over $2 million through these properties through free cashflow and appreciation.  

I already own one rental property, which is doing great, with cash flowing around $500-$600 per month.

Hi experts, I have a question about net passive income from rental properties.Say I have passive loss (say -X) from investment property A, but have passive positive (say +X) from investment property B.For tax purposes, can I pool A&B together to net them to 0 on the whole passive rental properties income?

This would add significant value since 4-5 unit properties trade for 50-60% over our current basis. 

Should we have a LLC for the rental business that “rents” from us the property owners?

I'm not sure what all info you'd need to give relevant advice, so here's some random info about the property. - The seller has no interest in keeping the property (I guess that makes her a motivated seller?)