The biggest drawback I am having is calculating cost for repairs & finding a reputable contractor for a fair price - I know nothing about renovations right now.  

I was wondering if anyone could provide a recommendation for a reputable property management company in Northern NJ that handles small multifamily? 

With that said, not every mortgage broker has an exceptional reputation.

Does anybody have any reputable sources?

That honestly doesn't sound too bad I'm sure maybe if you asked around you can find someone who can do it for slightly cheaper but if they have a good reputation and I would go for someone who would do a better job. 

I don't know the details, but Cross Country is a reputable renovation lender, and has the VA product.

Would anyone know of a good and reputable resource or platform to learn and execute investing / buying  mortgage notes?

They can network effectively with placement agents - Agents are going to be the primary way a house is filled, so a reputable manager likely will have multiple agents who are willing to work with them already because they have a history of running good homes.

I would suspect you would be better off talking to a reputable turnkey provider.

Tenants all tell me they'd much rather rent from an individual landlord, the big PM companies have bad reputations apparently.