I have redone the kitchen and opened it up for open concept look, bathrooms, floors, pool deck, added an outdoor kitchen, added a 4th bedroom and re painted inside and out.

And, you're going to have to fill them every year, which means you deal with advertising, tenant screening, make ready costs (cleaning, repainting, carpet cleaning or replacement) once a year.

To get a higher appraisal amount, I would like to repaint the house in order to make the house cleaner.Is there a solution that would fix the smoke/nicotine stained walls and keep it from being stained again?

I plan to repaint all of my rooms to a neutral color.My concern is, would I regain the money put into installing the floors plus some?

The elderly ladies decided to crank the a/c so cold (64deg F) that the subsequent heavy condensation forming on the old metal venting started dripping through the ceiling tile & dining room light.They finally compromised with a higher temp, bought a dehumidifier & have repainted the ceiling tiles. 

The thing is, properties have issues that pop up after inspections, kids break in and repaint a room for example (LOL) so, yes, justify your offer.

They hide dirt much better and need repainting less often.

Do landlords generally fill nail holes and repaint before the new tenant moves in?

generally, it's the owner's responsibility to repaint depending on your contract, because most good paint life is ~3 to 5yrs in rentals 3. does the carpet need replacing? 

Our work consisted mainly of repainting the whole place, inside and out, which included replacing a fair amount of the trim boards on the exterior, installing new copper gutters and flashings, a few minor repairs to the slate roof (no leaks), a new driveway and garage floor, new garage flat rubber roof, renovating 2 full bathrooms that we used a lot of pretty expensive tile in, all floors except the sunroom had hardwood floors that were sanded and refinished, the sunroom had a travertine floor installed.