None. The coastline is fractal - as you look at it at greater and greater scales, it reveals more detailed folds and therefore is longer at each scale.

Being as the total coastline is already infinite, a rise in sea level cannot make it any longer. So the sea area cannot increase. (Also see Wikipedia - Gabriel's Horn and the Painter's Paradox).

Actually, the sea areas near the land will now be deeper (until sedimentation onto the continental shelf catches up) and will be less efficiently warmed by the Sun and more efficiently cooled by water exchange with the ocean depths. So I would expect a rise in sea levels to reduce significantly the evaporation of sea water close to land.

I would also say none, but for a different reason.

The Earth's oceans and atmosphere as a whole can be considered to be in equilibrium in terms of temperature and evaporation/precipitation. The surface area of the air/water interface would only affect the response time of the latter to rapid changes of temperature but would not affect the ultimate equilibrium state which only depends on temperature.

Since global climate change is a gradual process, the response time referred to above is of vanishingly small significance and, therefore, so is the surface area of the oceans.

Well, I think that if the amount of water increases, the temprature will decrease because water cools and gets heated slowly.