As far as your question as to snorting it rather than just taking it orally, certain medications have a better bioavailability through intranasal/snorting the drug, it gets absorbed through your mucus membranes and sinuses, as well as the blood vessels and capillaries.
Oxycodone is one of these drugs. The better the bioavailability, the more of the drug is absorbed by your body and not wasted. People who prefer to inject (myself included), get 100% of the bioavailability since you are absorbing 100% of the medication, right into your bloodstream. (I am not at all trying to advocate or encourage anyone to try this, because it can, and will most likely result in a crippling addiction.)
However if a medication is combined with ibuprofen or acetominophen/tylenol/apap (like percocet, vicodin, etc), then snorting or shooting the medication is no longer an option, since these meds are not water soluble, and snorting or shooting that would be dangerous, and a waste.
Aside from the fact that snorting it would allow the user to feel more of it, the drug kicks in faster than if it were taken orally. More than twice as fast.
Of course there are exceptions to every rule and the facts I mentioned aren't necessarily applicable to every single compound and substance, but it's generally a rule of thumb as far as oral, snorting, shooting.