The advice I've seen when receiving a life-altering sum of money (including the sale of a property you might have owned for a long time) is to put the cash in liquid savings and then become financially literate.

Can the window be altered? 

Usually the cost is 1/2 mo rent to listing agent plus 1/2 mo rent to renters agent, you may be able to bargain down the listing side because the agent will get calls about your property they may be able to translate into other business.

I'm sure the new furnishings look really nice and probably translates into higher rents? 

My experience from flipping houses has really translated well into renovating these smaller apartments:When I transitioned into commercial real estate investing in 2012 from starting with zero nada (infact I dropped out of business school to get into real estate but found myself waiting tables instead) in 2008 it was a whole new world.

And how does it translate to a deal like how do you contact owner/seller?

The knowledge can be generally translated into apartment buildings.  

Yes, you can alter openings in masonry buildings. 

This will translate directly into invaluable leadership skills that will last a lifetime. 

It's better to look through your options earlier than alter when it comes to anything legal, because once any type of legal action is taken, or even threatened, you will not be able to restructure.