I started following BP this past year and pulled the trigger on a multifamily 4-plex here in Phoenix. 

Also consider fire safety systems and security systems. that's a good point. imagine if the original owners were not forced by the city to install sprinkler systems and the new one is forced to if it triggers an alert with the city. that would be a deal breaker.keep in mind upkeeping exterior on a highrise is crazy expensive. u need cranes, lifts, etc, etc..

I pulled the trigger a little over a year ago on a part time flip.

I am hoping it will trigger some added value with finished hardwood floors and a basically new bathroom and updated kitchen.

You could always ask your dad to put eyes on the ground if you are considering a property before pulling the trigger. 

Just make sure she does't transfer it to her kids by way of a deed as that from whatI know would trigger capital gains. 

That's when you start to know your market and when you have a grasp on property values by area, then and only then are you ready to pull the trigger and buy something.  

How much income must the property generate to make you pull the trigger on a sale. 

The loan might trigger UBIT tax which can be as high as a brutal 39.6%.  

Just keep educating yourself and above all, pull the trigger at some point to get your feet wet.