They like to back out of deals when we have multiple people going in and out and legally allowed to deny us a walkthrough. 

Quote from @Brandon Larson: Yea, @Nathan Gesner is that legal to enroll someone in an insurance policy and then charge them for it?

My thoughts are to do an addendum (but not sure how to word it since she will have pre-paid her part until may) and let them figure out the security deposit between themselves at the end of the lease.

NJ is very tenant friendly state on the legal side.

The fact that you think the tenant is a pain has nothing to do with how you maintain the property, you could be creating legal and maintenance problems for yourself by not taking action. 

I don't want them coming after me legally if I sell.

And you can't legally dictate how much they carry for personal belongings. 

- FYI: it's only illegal to try to rent it out, the property owner can usually legally live in a nonconforming basement unit.If you do all this you may still negatively cashflow each month, so make sure your income can cover and/or your cash reserves.If you do this successfully, you will learn more in 1-2 years than you would reading here on BP for 5+ years:)Good luck:)

As long as they pull the proper permits and are licensed contractors (if required in your state), they can legally work on the property.

If they had not moved out, i would have brought in the best attorney available and charged the tenant for the legal costs.