Off-Market Short Sale?

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So I've begun direct mail marketing, and received several calls. Most are the usual "Why are you mailing me, how did you get my info?!" However, I found one motivated seller. Here's the situation...

Underwater in his mortgage.

Behind in payments.

Has moved out.

House needs a bit of work - roof leak & replacement window(s).

The owner says he plans to "give it back to the bank."

I'm thinking this might be a good opportunity for a short sale. 

Does a short sale need to be listed on the MLS for it to be approved? Can I work with a RE Attorney on the short sale rather than an agent?

I was considering calling his lender (DiTech) to ask about their short sale requirements, and see if they are able to share any info about this property. Any suggestions on what to ask?