I've already invested in a duplex in NJ (I'm renting it to two families and managing it) and a single family in MI (living in it).

Income is $600,000 per year and husband and wife both work full-time non real estate jobs.
Is it true that the tax benefits are greater, or realized more quickly, on purchases like furniture or televisions to itemize...

I planned to develop another home in the back half but a contractor inquired about renting the lot for their construction trailer so I’m pausing my development. 

It had never occurred to me that one could be self-sustaining through one's own resources, mainly because I had never made an effort to understand money management, retirement, or finances in general.An MMM blog post led me to BiggerPockets, a forum where the members, sophisticated investors, referred to their properties as "doors."

Take a look at some trade accounts and a line at the Big Blue and Big Orange if you are going to self manage.  

Does anyone have a recommendation for a property manager?

How many units or homes are you managing?

You're looking for increased cash flow, so managing more doors and/or strategically utilizing leverage can make a certain sense there...but as you mention financing costs aren't as rosy as they were 2-3 years ago. 

New investor here looking to build my network out with property managers in the area.

I’ve contacted some property managers and I think it’s a good investment.