Yes, a mash is a mash no matter what the volume of malt is. You can do a 45min mash, or 60 or whatever. The longer mash results in a drier wort in the sense that theres more fermentable sugars vs the larger "chunks" that lend body but will not ferment. I'd also mash around 150-152F vs 155-160F, this will also give you a more fermentable wort.
The longer whirlpool is fine as long as you're chilling quickly. If anything its better to get the trub down and piled up in the middle of the kettle.
Dry hopping, I haven't that much experience with. I think a week is adequate, if I needed more flavor I'd add more hops before going much longer than this. Although I have thrown a sock of hops in a serving keg and left it thre the whole time I was drinking on it.
Not positive about Abrasive, I just loooke dit up and saw IIPA so I gave advice for a high gravity beer. YOu might be carbed up in two weeks, I just have had my higher OG brews carb more slowly, plus they are always cleared better at 4 weeks although that doesn't stop me from drinking half of them.