If tenants do that, can the landlord ask for expenses to clean up anything left behind (or from anything similar for example spray-painting something or building furniture)?

It might show better furniture verses if it was unfurnished when you first posted it.Get it listed ASAP and check comps in area for pricing, the 15 month lease is great idea,, @Matthew McGuirk          Say great lease terms be flexible.. 

Most of the damage is from moving furniture in I presume.

Outdoor recreation event but really for many things you need parking.

It it  might be valuable to somebody (sentimental, or furniture/clothing/household stuff, etc.) then it's best to file an ejectment lawsuit.

I noticed the moving boxes and furniture (couch) smelled really bad of cigarette smoke. 

When replacing, it is always better to replace both indoor and outdoor units at the same time, as they work together as a system.  

@Shawn HolsappleOne of the problems is that I face is that there is no outdoor storage or basement so the mower would have to sit in the yard or I'd have to buy a storage shed. 

Furniture wears and some things like couches need to be replaced every few years.

I have not thrown in other things like the cost of getting the house ready to rent, legal fees, accountant fees for filing taxes, advertising fees, costs of furnishing the house with beds, TV, maybe even cook ware or appliances, and regular furniture.