So, I usually see new RE investors get their best starts by jumping in and buying something manageable.That said I think you are wise to be careful to invest in a seller's market.My advice: dig hard to find a deal then jump on it.

I know we can get some market research like state-wise from the Realtors association (like this one https://www.njrealtor.com/research/), but if I want to go deeper and understand the market in a county or even in a specific city, where should I go?

Realtor wise, only know of one.

The two requirements valuation wise in order to defer all tax in the 1031 are that you purchase at least as much as your net sale and that you use all of the proceeds in the next purchase.  

I'm sure if you think on it you will make a wise decision. 

@James Wise I will definitely give that a read.  

It'd be wise to call and vet them out, the rates are around 7-8% for multis, some have fees on top of that, some do not.Shout out to the local REIA, they meet about once a month if you're interested:https://www.meetup.com/Rogue-Valley-Real-Estate-Investors-Network

I say potential because you don't even have to be under contract during that time but it's certainly wise given the velocity these days.  

I bought a house in Trinidad 6 years ago and am doing great on it cashflow-wise, even after a cash-out refinance a year ago where I pulled out 100K in equity.

There's a proverb about penny wise and pound foolish for a reason.