No big deal on the steeping grains. There will not be less fermentables because you were steeping and not mashing. You have probably extracted some additional tannins from the grain, but I bet you will be unable to notice it. I have a book called "Brewing beers like those you buy", Dave Line, 1978. His method for brewing leaves the steeping grains in the wort for the entire boil. We know better now, but this indicates it should not be a big deal.
The yeast is the big issue. 100F is the recommended re-hydration temperature for a lot of dry yeasts, so you should be OK. I would recommend you get a spare pack of dry yeast and be ready to pitch it tomorrow morning if the current yeast doesn't show any signs of life. If it starts, everything will be OK, and don't worry about any off flavors, chances are you will not notice them anyway. You are making your second batch, you want to make drinkable beer, and that's what you should get.