What they do off the property isn't your concern, until and unless they bring it inside.If they are smoking inside, agree with others to go ahead and remove them if you wish.But if them "getting away with it" is to completely leave your property and smoke at the street, I'm not clear on your issue.

Irrespective of whether you claimed it over the years or not.For the past I can't, unfortunately, tell you how to fix this and if it's even possible past the 3-year period during which you can amend your returns (which you probably should do together with a CPA) But what I would recommend is to file for an extension with the IRS so you have more time to have a CPA look into your situation rather than rush into a (mostlikely incorrect) filing.

Yes, you will make some money on the cash flow and some years will be better than others but what you will probably find over time is that after 5 years you are only slightly ahead in terms of income.

I gave her a heads up and she was able to cough up the balance minus the fees.

We are in for some VERY interesting times just ahead. 

So go ahead with the purchase even it is a manageable negative flow.Are there other costs associated that I need to know about?

It is also public record.Also just to give you a heads up, the foreclosure market has also gotten much more competitive.  

I think I will just go ahead and attack my debt full-force so that I can begin on reducing my school loans as soon as possible and begin investment savings sooner.

@Dylan Bensinger I would go ahead and give her notice to vacate/non renewal of MTM and move on.

Just be sure to vet the renters well, dont rush into just putting anybody into the house for you run the risk of getting crap tenets who may destroy the house after you just rehabbed it.