If you can see a bit of the old stem, that goes upward. If not, I'm sure somebody will be along who can explain it better than I can.

Dahlia don't need a lot of water to sprout, so if your soil is damp that should be sufficient. I can't see the tuber so I'm not sure exactly how dry they are, but if they're really, really dry an hour soak in tepid water (call it 75 degrees) before planting wouldn't be a terrible idea.

Also, if they're really badly off and you're going to lift them promptly around the time you get frost, I tend to dislike planting them too deeply. I just did the same thing and planted my tubers about 2 inches deep. Next year I'll plant them at more normal depths when they haven't sat in unknown conditions until far too late in the season.