Over the long run everything appreciates, but there will be a dip coming in some capacity so I’m not sure that fits either. 

Then what timeframe is the most vital to you, short term/mid term/long term? 

I have been thinking through housing, affordability, and the effect on what until the last few years have been dead markets.

Long when you need him? 

Less people are long term tenants here, though, so expect more turnover.  

Growing up in CAN I already had a head start in the rules, markets, etc, so the learning curve wasn't as long.

After 2 Duplexes ($80,000), we left with $320,000 so we want to buy another 2 Duplexes (same price) with 25% down payment ($112,500/each) since we are not living there for long-term rental which left us with $95,000 left.

It may seem counter intuitive, but the basics of real estate mentioned above are actually MUCH more important for long term success than the knowledge of any one technique or strategy. 

I view my primary as my long-term home, 3 young kids with a good school system, so this is where we are settled.

Does your friend want to rent out the rooms long-term?