I have noticed a flips on the market for months with decreasing prices and we aren't planning on trying to flip in this market. 

My goal is to decrease my taxable income and have 35 k a month for retirement in 20years.

It is located in a realitively small town with diversified industry and very gradual decrease in population.

Also, I'm not sure I'm following why your ROI with decrease the longer you stay in the home especially since you plan to rent the other house out.  

Make sure you reach out to some agents, check your local municipality business page to know any upcoming business coming in or closing down, research the market(employment, population:increasing/decreasing, etc) again all of this is available online. 

We know that we are dealing with the bank, and that they typically follow a pretty strict price decrease structure.

Advantages of paying of primary home mortgage#1 Ability to borrow on your home in the future increases as your principal decreases#2 One step closer to financial freedomDisadvantages of paying off primary home mortgage#1 Loss of tax savings from mortgage interest.  

I notice a trend of Sfr's sitting on the market for longer with decreases in asking price and a few of the over priced multi's are sitting stagnant as well.  

Diversification decreases risk in some ways#2  How would a relatively new investor learn about new markets and expand their knowledge of REI if they stayed in 1-2 markets only?  

I have a few SFH and MFs but as I get more units, the passive part decreases without a PM so I'm looking to get into Syndication to make it truly passive.