1.070 is borderline for multiple packets. Frankly, if I only had one, I wouldn't sweat it too much. I think you would be ok and the time spent worrying about it is time better spent making sure your beer is fermenting in the low 60's. That's going to be more important to the finished beer than if you underpitched a little.
And I've personally started rehydrating. Lots of people don't and make beer, but even the dry yeast manufacturers are recommending it now.
For dry, US-05 is great, for liquid maybe WLP001. Both supposed to be clean American Ale strains.