Even with the fan these units tend to get mildew on the walls above the shower so we're trying to figure out other options.  

You will need a separate air conditioning system or heat pump to provide cooling.If you have radiant distribution system (in floor, wall or ceiling) then it is often possible to use the distribution system for heating and cooling.  

He came back with nothing, as he did not see any sign of leak ( no peeling of wall paint).Solution: Tomorrow, I am planning to inspect myself and try to find root cause of the problem.

It can lead to cracks in walls, separation between ceilings and walls, and broken plumbing in walls.

Think new windows and R-19 wall insulation, R-50 ceiling insulation.

The front porch wall sconces were too round, the boarder for the flower planter should be made of the original brick from the home and not stone, and the list goes on.

Depending on the city and inspector you may need to have drawings made and open up walls but at least it will be legal.

Phase 1: Demo/Interior Framing layout walls and rooms. [10 days] Demo whole house/clean up interiorExpand walkway between living room to eating are by 3 feet (install new header)Frame up new laundry area, frame bedroom wallFrame up new patio sliding rough opening and install new sliding patio doorFix water damage floor in hallwayTile bathroom floor and wallsInstall rough electrical throughout house.Install rough plumbing throughout house.Install insulation and drywall sheetrockMeasure windows/door.

.- After few months you'll go to see hour condo and you will find maintenance issues not taken care of like scuffs in wall because of luggage.

If it is a sf, I hate to reward bad behavior, but I may opt for the earlier post option of retaining the tenant, maybe with understanding  they smoke in a designated open or vented area.