It should last a very long time as long as it's properly maintained. 

I have a partner that is willing to co-sign because he has proper paperwork including these pay stubs.

Because if you look at the cash you receive through a refinance as "free money" you are unlikely to treat it properly. 

A skylight that's properly installed with the right sealants shouldn't have any immediate issues. - Be prepared for maintenance.

I am in the learning phase, right now I am figuring out if I using this calculator properly. 

The proper chain of events would have been:Tenant hangs clothes>clothes fall down>tenant notifies you via your trouble ticket system (formal, text, whatever) that shelving fell down > you fix or arrange for someone to fix shelving and thank tenant for letting you know. 

This is a good time to start bringing a team of professionals on board to help keep your project cost effective, completed to the proper codes and standards and completed in the shortest time possible.2.

Deal sourcing: If Brokers aren't taking you seriously, then you're not approaching them properly.

I'm just wondering if he has just up and left (owes 2 months rent) What is the proper procedure to legally clean out and re-lease the unit.

-Are there any sites you are using to look at similar buildings to model your CAP rate expectations off of on the purchase side to make sure the current value is being calculated properly?