However, even at your net worth now, you will likely have to continue working well past the age I would like to retire in order to ensure you can draw off those investments long enough.  

What is the age of the property?

If the person sitting next to you is late 30's, looking at another 25 years of daily grind, and sees you are 5 years from retirement at the same age, they will get jealous.I am with others who keep real estate business hours communications to texts and emails, and take calls at lunch / before /after work.  

In this day and age it's a wonder he didn't end up at Guantanamo Bay I guess.....:-)In my opinion, a business card would be a likely choice.

Age of house requirement?

Now, when I sell, then the market CAP is of interest.I would need to know more about the local economy, the building's clientele, the business' performance (is it operating efficiently, if there is room for improvement, how much), the age of he building and its degree of obsolescence and deferred maintenance.  

I hope to start out using creative investing strategies that require little money down, because I am a full time student and do not yet have established credit due to my student loans and young age. 

My fiance and I are discussing marriage within the next year or so. We're also discussing beginning investing in real estate with a focus on single family flips, or multi-family buy and holds for the first few purchas...

Be sure when running the numbers you allow for vacancy (I assume 10%) and maintenance (I start with $100/mo and adjust based on the age of the property).  

Take it from a licensed but non-practicing attorney who got traction on 2 mobile-phone calls made, whilst seated in buyer-agent's office, to Vanishing Listing Agent.