Make it nice, have curb appeal, decorated nicely, ect. 

My inherited tenant, in my first ever rental property, refuses to pay rent and has lied through her teeth the whole time.

Honestly it is a mess because if the landlord is a jerk or tenants lie, it could become an argument of where the rent is. 

you could use the cash for a higher down payment for the seller financing to make it a bit more appealing to the owner.  

I wouldn't lie on an application for a loan.

Her response was they are not obligated to merge the cases, they typically don't merge the cases (which I still contend was a lie because I see cases merged all the time), and it's not their responsibility to worry about surplus because the third party purchaser wasn't smart enough to look at the property history.

We will be putting down a fair sized down-payment to avoid PMI, so offers like 3.5% down aren't that appealing to us.

Curb appeal is important as well as amenities. 

I was repeatedly lied to, neglected, and in the end, assumed that I wouldn't review their (incorrect) work before signing.They told me everything was smooth sailing (including calling me 48 hours before closing to confirm that I was good to close) up til 2 days before my closing at which point, it was revealed that no action had been taken on my loan. 

tenants have some unrealistic expectations if they rent an old home that isn't super insulated and airtight.Even the electric companies and DOE recommend only setting the thermostat to 78F while at home..If they want cooler than that, get them a meat locker or freezer chest, and tell them to go lie in it.