Unless you are planning to create a flipping business with multiple crews, this becomes a job.  

I have a private investor asking from assistance to purchase multiple properties this year.  

The easiest way to start to get a feeling for the value is to look at multiple comps in close proximity to each other and analyze the differences in the properties and the different in rent. 

My ultimate goal is to build passive income over time by having multiple multifamily homes throughout my state of residence .

I  use sellers agent for this property. i believe in this strategy - going with the sellers agent, in LA hot market this is an  advantage non cash buyer can get when there are multiple offers.

There are multiple levels of investors hear.

If there are business reasons to have an entity, by all means, see your accountant.You only need one LLC, not multiple LLCs, also check on a Series LLC. 

I have purchased multiple properties from the same tired landlord over time before as well.  

I have done it multiple times and been total transparent with the mortgage companies.

Most of the NOO portfolio lenders I am currently seeing are looking for multiple property blanket loans.