I realize that once someone creates a letter of intent they can start on the due diligence phase to learn the financials, physical, and legal but what else can I learn about a property before making an offer? 

The benchmark is what people do for pro formas and try to re-write history in the future, it never works that way.I've been deeper than anybody here in physical asset investing, albeit not REI, and it's just not the case that history is relevant.

It's how it goes in physical asset investing.

Never the less, I agree that you need to physically be there and check on your investments. 

There is an old joke: you don't have to run faster than the bear, just faster than your friend.There are hundreds of leases signed every week, your apartment needs to be more attractive than 50% of what's out there and it will be rented quickly.So you'll have to do some mystery shopping and (ideally) physically look at your competition.

Don't forget RE isn't a 3 year hold...10 years (less with other benefits from above included) is not a long period of time with a physical asset.

The house is needing some repairs, but have not physically looked yet.

I'd break it down into two steps.  1) Move-out & physical damages.  

They will likely have an edge over you due to their local expertise, relationships and physical presence. 

The main issue here is that you had to send a physical check to a "new address" to return the deposit.