If possible, check online reviews or ratings and, for larger projects, consider a local project manager or inspector to oversee progress.

The problem with learning about any type of business/investing on Youtube, books, etc. is that many of them don't know what they're talking about and are not real estate investors, they're online course peddlers.      

I'd recommend Appfolio since you're managing more than 50 doors (their minimum criteria). 100% of the PMs I've worked with for my own rentals have used Appfolio, and it's always produced great owner reports.For overall bookkeeping/accounting needs, I always recommend QuickBooks Online since my bookkeeping firm uses it exclusively for our clients who are all REIs.But, for a PM company for the trust accounting, I usually recommend Appfolio.Hope that helps!

Plenty of realtors go for eXp Realty, a primarily online brokerage, as a relatively low fee low commitment brokerage 

I was online searching for a home address --seems to be difficult to find him. 

Quote from @Kefah Al-Ramahi: Quote from @Eliott Elias: GC is going to be toughest, don't hire off of Facebook or online sources.

A lot of people online make it sound like a nightmare, but most of the trouble comes from not knowing what you’re stepping into.

(This was all a lot easier to do before information became so readily available on line).  

What online PMC software are they using?

I'm looking to do a cash out refi on a duplex I have, but I cannot find any reviews online or much of an online presence for them.