Hope this clarifies some issues.As a property owner / manger you do want to know who may be acting irresponsibly, violating rules, or who damaged property.  

How do you communicate with owners?

Owners often view their multi-unit property as one entity, which can lead to frustration when issues arise.

Just wondering if property owners here retain property tax consultants or attorneys to help fight increased assessments, classification changes, or other issues with their property?

@Cody TuathaDe, you might not have seen the conversation started by @Alonso NoriegaMy suggestion is that you get a HELOC or a fixed rate second mortgage on your property before you move out, so you garner the benefits of owner occupied rates.  

I'm interested in buying the property and would like to see if the owner has any interest in selling the property for a reasonable value.

Start negotiating with owner to go under contract.

I own an owner-occupied duplex in Philadelphia, and each unit is equally 800 square feet.

So is the main items for NOI:1. operation expenses (i.e. owner responsible utilities)2. property taxes3. insurance4. maintenance & repairs5. vacancy rates6. snow plowing  (or is this until maintenance?)

You may not get the same rent as you did with the prior owner but at least you can stabilize the property in the short term, pay down the mortgage and reassess in 5 years.