This is actually quite a sizeable chunk. If in the future needs grow 10 times the area needed might become big problem.

It would actually be much better than nuclear. Remember, for every kWh of electrical energy delivered from a nuclear plant, 2 kWh of waste heat goes up those cooling towers. This is not the case with solar, particularly if it were built on ground that was already fairly dark.

Direct thermal pollution like this is not yet globally significant, but if demand increased to the point that land constraints actually applied then it would become important.

Might.