153 IBU's will be fine. You won't notice much of a difference even if it was 90-100IBU's. It'll be great. Oh and with this recipe, the hop smell in the house is outrageously wonderful--love it. As far as 1 or 2 packets of US-05, I have done both. 1 packet knocked it down, but 2 packets knocked it down a little bit quicker. Either way is fine, totally up to you, I usually use 2 just to be safe, but it isn't necessary. Enjoy.