Are the hops pellets vacuum sealed? If not, and you don't know how they were stored, I'd be very skeptical.
For an Amber Ale, I'd use the 6.6 lbs LME, and a lb of the crystal (steeped), which should get you a gravity in the mid 40s. The color will probably be a little on the dark side because it's LME. (I suggested using the LME because I think DME keeps better, so I'd use that for a later batch.)
Split the cascade 1/2 and 1/2 between 15 minutes and 2 minutes additions for flavor and aroma.
If you're boiling 2 gallons, then the whole ounce of Chinook for bittering would be about right. If you're boiling more, this might lead to too much bitterness.