I might be eating these words later, but as far as I can tell, at least here on the Oregon Coast and beyond the market crash everyone is waiting has not materialized. 

A month-to-month rental is typically priced higher, which means you may be worth $4,000 - $6,000 per month.I highly recommend you research your market and understand the value of what you are renting.

Whatever is cheapest and most durable for your market!

My initial question, does anyone know what's involved to invest in a US market as Canadians?

The RE market is a semi efficient market.  

Detroit is not a market to play around in without a professional on your side.Remember: cheaper doesn't mean you'll make more money.Start by going to www.narpm.org to search their directory of managers.

Whether they are section 8 or market rate, a bad tenant can cause $10's of thousands of dollars of damage really quickly.  

The banks are just very conservative in this environment.I met a gentlemen who came into my brewery (current location that I lease) and we got to talking about the general market and our plans to scale. 

I am sure, alas one cannot specialize in all markets:)

The market appreciates 3% per year.Pay cash for one house and rent it for $1,500.