@Tom MatousekFirst off...switching realtors (brokers) at this point is going to create some tension as you are technically the buyer of the agent you already wrote the offer through.

Also, be aware that this may cause tension between you two, especially if it is a new relationship and new venture for both. 

Outside of that, I filled the apartment upstairs at market rate and I'm concerned that chatter between the tenants could create tension in regards to price.

How wide can the wealth devide grow, before the tension gets too high?

I'm not saying that everyone from Serbia will dislike everyone from Bosnia and or vice versa, but I can tell you from experience that there are some tensions there.

I disagree that anything can be fixed for a price.There isn't enough money in the world to get rid of a freeeway next door.No investor could spend enough for a residence to "fix" high tension lines overhead, or a county dump right next door.There is nothing that can be done if all the local wells are contaminated or dry, and there is no city water.

Now screaming and cursing can sometimes relieve some anguish/tension but look at the bright side you still got a deal on some of the properties that are over $50k closing...

The agreement should address the initial participation of each member (i.e who contributes what money and which skills); the ongoing responsibilities of each member;  procedures for exit of any of the members (both by choice and with a push) - e.g. to whom may they sell their interest, who has first right to purchase the interest, etc.You may likely think such a formal agreement an unnecessary expense at this point and an activity which may put tension on the bonds of friendship.  

I take them out when broken and add a cheap tension shower rod and attractive grommet curtain.

This provides a tension layer that basically replaces the reinforcing bars that have been exposed in the spall.