Although you definitely do need to go to the doctor, sucking on peppermints will soothe it in the interim. Not all sore throats are strep, but if it is you need medical treatment. Right now I have a really sore throat but went to doctor and mine is NOT strep. You should avoid self- diagnosis!
Yes, both these recomendations are true. Salt water will help with the pain and reduce swelling (be sure NOT to swallow it) and antibiotics are very necessary because without them the strep virus can potentially spread further down the esaphagus and infect other more vital organs!