I've had my question answered except one part what are the realistic chances of throat cancer in 20s?

Not too high. Chances of having throat cancer are not too high unless you are a smoker. Smoking greatly increases the risk of cancer. If you don't smoke & have acid reflux (you may not even know you have it) it can lead to barrett's esophagus, which is a precancerous condition. However, only about 1% of barretts will progress to cancer. Keep in mind, cancer risks do not always follow stats. See dr if concerned.
HPV. Although i agree with the other answers, in the last 5-10 years hpv has become a major contributor to throat cancer. Throat cancer related to hpv can occur at an early age and is not related to smoking or drinking. If you are at high risk for hpv and have concerns for possible throat cancer, you should be evaluated by an ent.
Unlikely. Throat cancer is most common from continued smoking augmented by heavy drinking. This is a length of time and exposure issue and if you are in your 20s have had a short exposure at worst. If you smoke or drink heavily, this is a good time to reconsider.