Fr your first question, I've used a muslin bag to hold the hops and then just pull the bag out after whatever amount of time you want. If your beer isn't clear enough at that point then you can just put the airlock back on after you pull the bag of hops out.
I have also waited 2 weeks before I even start dry hopping the secondary. It's your call really. Since this is for an IPA, I would wait however long you think you need to and then dry hop that final week before bottling. That will give you the most fresh hop taste when it's time to drink.
Kegged: Nothing :(
Bottled: Chocolate Stout, Barleywine, orange-cranberry mead
Primary: Full Nelson SMASH!!!