I think you've got 2 problems here:
1) The first is that the hop aroma disappeared almost immediately after
opening the bottle..... I let the wort cool in an ice bath, and it
took about 2 hours to cool.
These two things are connected. When you add the Cascade hops right at the very end of the boil, their purpose was to impart some nice, American-style hop aroma to the finished beer. Unfortunetly, since it took you 2 hours to cool down, virtually all of that hop aroma was lost, as the hops continued to sit in the hot wort too long. Think of it like over-shooting the temp on a nice medium-rare steak. If you leave it in too long, you'll end up with medium or medium-well, which is still nice, but not what you are looking for.
To get the chill done faster, there's a couple things you can try for next time. You can simply add more ice. Just buy twice as much and drain off the melted water after 20min or so and add some more. Another tip is to continuously swirl the ice water around the carboy/bucket/kettle as it cools, like an ice cream maker. Ideally, you should swirl the liquid in the in the opposite direction of the ice-swirl. That helps a lot, surprisingly.
Also, you can do something like boil down to 4 gallons of wort, then pull a jug of sealed, clean water out of the fridge, and pour it into the wort to hit 5 gallons. This will drop your wort a fair bit right off the bat. You want to get down past 170F or so as fast as you can, the rest of the cooling down to 65F pitching temps can take a little longer, but above 170F and you are "cooking off" your hop flavor.
If you continue to homebrew, and you love hoppy beers, you'll eventually need to buy what's called a "chiller", which is a device used to cool wort down quickly, but it takes some $$$ up front.
As a last ditch effort, if you just can't get that kettle cooled down under an hour, take whatever hops your recipe says to put in at the end, and add them as "dry hops" instead. Heck, DOUBLE that amount! Honestly, DIPA needs a heavy charge of dry hopping to achieve the style anyway, in my opinion.
2) The second flaw was the color, it had much more of an amber color than
most double IPA's I have seen.
This is a very common (minor) flaw in extract beers. Here's a tip that's not immediately obvious: you do not have to boil all the extract for 60 minutes. What you are doing is boiling the HOPS for 60min to achieve the appropriate bitterness, and you have to do this in wort (not plain water), BUT you do not have to use all the extract up front. Just put in, say, a quarter of all the extract up front, and boil for 60min with that. With maybe 10min left in the boil, add the rest. Sounds crazy, but once you consider that extract has already been boiled down into a syrup, you boiling it for 50 extra minutes doesn't change anything.
What happens when you boil the total extract together is that you "darken" the wort, like cooking caramel too long. By diluting the concentration, you stop this from happening.
Finally, if you first batch was just a little too dark, and didn't quite have enough hop aroma, I'd still say you did a great job. There's a LOOOT worse that can happen. Best of luck.