1- Per White Labs "Ale Yeast will survive up to ~90 F", so if you pitched at 100 F it's dead.
Most people would say that you should make a starter almost every time you brew. Everyone would agree that a starter would improve your beer, especially with such a high OG. If you use Jamil's yeast pitch calculator http://www.mrmalty.com/calc/calc.html
you get a suggested starter size of almost 2 liters for that OG, that's a huge undertaking for a single vial of yeast, and one that might have made the lag time over the 12-18 hours you waited before seeking out yeast #3. Depending on the amount of nutrients and oxygen in your wort, the yeast may still have been building up its energy supplies to begin producing alcohol, so you wouldn't have seen a drop in OG.
Not much experience with champagne yeast, but my understanding is that it's very dry, and certainly won't give the flavor profile you would get from using the English strain you started with.
2-It'll ferment, and it'll be beer, so drink it up and learn more for the next batch. Patience is the most difficult part. RDWHAHB