I didn't read the info on the box but the enclosed information with LED's that I have bought from three other manufacturers explicitly say NOT to use them in enclosures due to the heat they generate. I'm going to assume the same for these as they have fins that are impossible to touch when on.
Not these. The operating temp suggested on package is more or less indoor, and they should not get wet.
Manufacturers say not to use these in ceiling fans because the globes around the bulbs don't let them ventilate properly, thus causing them to fail earlier. These things generate a lot of heat. That being said, I have put these in one of my ceiling fans because the light fixtures have very widely flared, open-ended, floral glass. The glass is cool to the touch and I've had no bulb failures, fires, or globe shattering. You could minimize your risk by leaving the fan on (with the air flow directed downward) but you still risk, at the very least, decreasing the life of the bulb. The safest place to put these bulbs is where the generated heat can rise unimpeded by any objects or enclosures.
Correct, they come in sets of 2.
I didn't measure, but they seemed about the same size as a standard 100w incandescent bulb. They are a bit heavier than the bulbs I replaced however. Should work.