I can't imagine there's a huge market for $4500/month rentals in Newark.

If you are considering making it a rental I would suggest imagining having to go there at night.

This proved to be as difficult as I imagined it to be.

I am just guessing here but I imagine that well over 90% of the investors that make their way to actually see their operation in person end up pulling the trigger.. again just a guess but as someone with 4 decades of expreince at this.. and owning more than a couple real estate brokerages you can tell a well put together shop..  

In general, running utility lines to/pouring a concrete slab for the prefab home could be required, and usually isn't cheap where I live.

I can’t imagine paying someone 50 dollars an hour to do it.

I know investing in a different state can be complicated so I can't even imagine investing in a different country.

You are limited only by your imagination.

I would imagine that someone who lived in one of those properties showed evidence of lead poisoning. 

I’d imagine you could do the bolt, bracing and cripple walls (basically plywood bolted with lots of screws to the interior walls) for under $10k.