Im assuming that I should-fill cracks with high strength cement and flatten out to match rest of all as best as possible. 

the risk comes from selling it as a how to super size your portfolio and get infinite returns.it leads ( especially out of state) investors to think they too can do this one their own..it can be done in theory NO doubt.. but its not something that most are prepared to handle and do first time out of the gate and from half a country away..  

I doubt you are making $5,300 a month positive cash-flow from 3 SFH's.I would have to guess this number to really be $300 to $900 a month depending on how lean the properties are.With that said - it appears that you need to gather a couple more rentals unless you both have massive amounts in retirement accounts.

I doubt it's worth moving anyway at this rate anyway since it's only 1 more house and they've been good so far, but good to know it could cost me.

There's no doubt a land value tax of that magnitude would create downward pressure on real estate prices.Your costs as a landlord just went through the roof as you've traded a beneficial income tax structure that allows deductions, particularly depreciation to modify your taxable income to zero or below zero for one in which no deductions are allowed and you owe every year...Not good for those who own rentals in my opinion.

My concern with simply buying out my in-law is that b/c the property is distressed, I doubt I could get an insurance policy to cover it until such time as I can raise funds to rehab.I appreciate your advice in this matter.

I have 200+ tenants in that submarket paying similar rents and I highly doubt anyone of my tenants can afford to make such a repair.

I have serious doubts if its been converted into a multifamily...I recently saw 150-yr. old tavern that was attached to the largest grist mill in the country get denied registration...Anyway, location is key...if you are in city limits, or have neighborhood (or deed) restrictions you may be facing a challenge...I know a guy that renovated 20-properties and discovered that the siding had to be replicated to the original...he had to pay a machine shop to create a cutter head so he could mill the siding to the original spec for any repairs.

But if in doubt, I handle it

I seriously doubt I would go through a refi just to lengthen a term.