For dryhopping, I prefer pellet hops. After 6-10 days, they typically sink. If any hop particles are left on the surface at that time, then a nylon mesh paint strainer bag from Home Depot, wrapped around the auto-siphon when transferring will help with that. The prime goal is filtering without introducing oxygen, which is why you should wrap the auto-siphon instead of transferring & splashing the beer through mesh material from a height.
Some people say cold crashing helps to drop out dryhops, but I beg to differ. It's the extended 3-7 days of added time that further helps any non-yeast/protein particulates to drop... not the change in temperature. Cold crashing IPAs in my experience is only beneficial for clarity purposes when you use a low floc yeast. I've skipped the cold crash for many an IPA, using medium-high to high floc yeast, and I've always had crystal clear beers despite using a ton of hops and no gelatin or clarifiers other than plain old whirlfloc in the kettle.