I use the MLS, I also have a network of wholesalers who often have some really good deals.The company I work for specializes in REI.

I suppose you know what the balloon payment is now, however most residential loans are NOT assumable and I read the ad as the seller selling as a "Subject-To" transaction as an all inclusive deed is a type of special warranty deed where the seller does not give clear title, title is subject to paying off the existing lien as agreed.

Is the subject property something really special?

Provide any references you think are helpful.....accountants, attorney's who specialize in real estate, local places to purchase materials, where to get discounts, etc. 

What makes mobile home park special (compared to apartment and houses).3.

its a pretty typical REO Transaction, I was a Listing Broker for Fannie for years, the process has changed a bit, but the basics have not, dont send them an offer of 50% of list an expect them to accept, just not gona happen (in most cases) the closing can be slow, but most REO's are, and be sure the title company gets a special assessment letter, its often missed.

The bank is giving a special warranty deed which basically means they are guaranteeing a title for the time they have had it in ONLY . ( not for the last 40 years prior to them taking it back) I did a lot of searching on my own and it looks good  .....  0 liens on the property .  

@Trey BrooksYou might consider Niche or Specialized Housing like student housing.

One word :LAWYERFind a lawyer who specializes in this and is willing to back you up in court.In Indiana, the company I worked for charged 2 months of rent for the lease breakage fee.

Just make sue the specialize in tax and have significant experience dealing with real estate investors.Here is a great list of questions to ask a potential accountant:http://www.biggerpockets.com/forums/51/topics/70447-questions-to-ask-a-cpaAlso check out the www.NAEA.org page in your search.