1. Lately for an IPA, I use 4 to 5 oz per 5 gallon batch.
3. 7-10 days
4. Secondary - Sometimes I'll add a couple more oz in the keg
5. I don't whirlpool. I don't have a pump and am too lazy to stir for more than 30 seconds at a time. That or ADD kicks in. Is that a bird? But I do add equal amounts if 0 minute hops as dry hop. So for an IPA, I'll add 4-5 oz at 0 minute and allow for a 30 minute hopstand before completely chilling.
6. Hoppy - yes, I am happy. This might sound silly, but the only thing I really like about double IPAs is the amount of hops. I'm not a fan of the heavier alcohol content and malt. So, I like to add more hops to an IPA with 1.065 OG. I like to use a combo of four flavor/aroma hops and use them equal proportions depending on hops at first wort, 10 min, 0 min and dry hop. I always bitter IPAs with Columbus. I feel it adds a funky/dank bitterness.
FWH - 1/2 oz each Centennial, Simcoe, Citra, and Amarillo
60 min - 2 oz Columbus
10 min - 1 oz each Centennial, Simcoe, Citra, and Amarillo
0 min - 1 oz each Centennial, Simcoe, Citra, and Amarillo
Dry Hop - 1 oz each Centennial, Simcoe, Citra, and Amarillo
If I would add to keg it would be 1/2 oz each.
I've been using this schedule with various hops for my last 5 or so IPAs and have been digging the results.