The cracks range in width from hairline to 1/4 of an inch and are larger when viewed in the crawlspace than when viewed from the exterior.

Neither is innocent and I’ve told them both multiple times that they need to act like adults and be respectful of the other (music and noise to a minimum during the day and nothing at night as stated in the leases.)

I know Zillow is not a binding appraisal system, but for it to be off by $60-75,000 in my price range seems off.

Not all price ranges  make good cash flowing investments. 

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Given that I'll be house hacking my realtor created a list that focused on duplexes but giving the cost of CapEx I can't really see duplexes within my price range, (below $115k), making enough rental income to sustain and cash flow positive long term.

Your rent will need to be in the range of 1% of the full market value of the home  ( or better) not 1% of the mortggae value if you want to see any return on your equity.If you can not get a minimum of 2K rent per month it would be wiser to sell the property.SFHs purchased as a personal home are very rarely a worth while investment as a rental property.

For what it’s worth, over the past couple years, my increases ranged from 3% to 8%. 

If you're working the sub 50k range, you're going to have a ton of deferred maintenance, problem tenants, and most likely a bunch of move-outs or evictions if and when you get the properties. 

I wouldn't worry about it too much, it conveys respect, or is meant to.Work with an attorney to develop a general contract with boilerplate language.