More common today then 18 months ago. 

A common thing I have run into is estimating repair values accurately.

I am really not sure, but I think it would be worth seeking legal council to avoid creating a bigger problem.I'm probably applying too much common sense and a moderate understanding of justice.

But since you are tenants in common right now you can separate or combine your interests as you want. 

@James ShortVery common scenario in Brooklyn/Queens.

The truth is, you could read 100 books and still not know enough because certain things need to be learned through trial-and-error.

If third party, typical management fee is 10% and leasing commissions range, but commonly 1 mo rent for new leases and 1/2 mo rent for renewals.  

This isn't common and not every title company will do it, or have let alone heard of this strategy.Here is another way:https://www.biggerpockets.com/...

So two separate items 1) deeded fee or common ownership 2) tax or assessor parcels.

Problems like trespassing, conflict, and unwelcome visitors are common to any multifamily unit.