Either through a transdermal patch (a patch that is placed on your skin, in which the medicine is absorbed into the skin over a period of time - in this case 72 hours, and then the patch is replaced) or through and IV.
Three hours is barely enough time to get the full dosage effects, and that's if you've already been using it. Patches can be reused, but only in cases where they need to be removed for emergencies,...
Yes, it should be ok. Hydromorphone is a type of opioid, which do not interact with ibuprofen. It should be safe to take in addition to the Hydromorphone as long as you stick to recommended doses.