First off, as you are travelling in Business class you are welcome to visit SAS lounges when arriving from a SAS intercontinental flight. There is an exception, not flights from EWR.
Make sure when arriving to follow the signs to Transfer and not Baggage. the
lounge is just past the passport control. If you go through to the baggage area, you will only be allowed back into the secure area if you have a same day departure boarding pass.
You have to have your boarding pass with you, as they exchange the key to the bathroom for the boarding pass. Ask when you check into the lounge.
There is everything you need in the bathroom including toothbrush and paste, disposable razor and cream. Enjoy!
When you're done showering, go down the stairs in front of the lounge to the baggage area, and find your luggage. If you can't find your luggage go to the baggage claim/ground service counter. They'll have them.