How do I get the physical address from this? 

You'll never get the money but at least you get rid of him.This is why it's important to inspect every unit before purchase (including physical inspection, payment history, lease terms, etc.) and why you should have a reserve.

The previous owner still has all their stuff in there but they are not physically living there.

It is a good idea to:Spur them into action to redeem; and/orLegally gain official possession of the property in case there might ever be some dispute about whether you were physically in exclusive and continuous possession.

In other words, a digital copy of a physical original is generally enforceable, but not 100% bulletproof.That said, I’d suggest holding onto the physical originals that you already have. 

I successfully eliminated all types of crawling pests larger than an ant from a duplex we own by physically sealing all holes that I found with caulk or even that nasty yellow gap filler stuff for larger areas. 

Good owners, you won't have any damage, but bad owners.. well if you ignore a dogs emotional or physical needs, your property will suffer, so just make sure you're aware of it.   

My main concern is that I don't have any construction background and I have never rehabbed a property before so I don't have any real world experience regarding the costs associated in doing so.Once I find a deal that looks promising on paper and I physically go walk the property with my realtor how am I supposed to determine a rehab estimate without any prior experience? 

You won't know until you physically check on your property. 

That requires a physical presence.