I wouldn't recommend sacrificing location quality for an initial investment, and maybe ever (and do it
very cautiously if you do).
That doesn't mean it needs to be a top of the line super trendy neighborhood either. But it shouldn't be a place where you say:
I would be looking at neighborhoods that I don't know, that I might not feel comfortable in.
To answer your overall question of "how to learn a market", it goes to one line you said:
I don't know how to research rents, or to figure what price / neighborhood is the right one for us.
You need to start looking at the listings in the areas you're interested in daily, both for sale listings and for rent listings.
Get rental comps from the MLS (not sales comps, rental comps), check sites like Zillow for their Rent Estimate and Rentometer.com and Craigslist. Know what houses sell for and rent for, and why, and what amenities and neighborhoods change that, and by how much.
The way to learn a market is to dive in and look at what is available and what it goes for, over an extended period of time.
You can't just read about a place for 15 minutes and "learn" the market. It takes time, work, and due diligence. (Or glomming onto someone who you trust that already knows the market and being able to use their expertise and knowledge.)
(I'm skipping past the macro view to the micro, because presumably you're already familiar with the local economy, laws, courts, etc. etc. - but if you weren't, or if you were trying to identify a market long distance, you need to start with the macro before going micro.)
Hope that helps! :)