Wrong. Oral cancer spreads locally to other structures in the mouth, through lymph ducts to lymph nodes and via blood to other organs, e.g., lungs.
Not so. Can spread locally more than distally. Can result in disfiguring surgical rx to remove tumor and lymph nodes. May need chemotherapy, and/or radiation rx. If you mean spread to other people, then consider that oral cancer, like uterine cervical cancer, can result from viral infection (hpv), plus the added factors of tobacco (yes, smokeless), alcohol (even xs mouthwash).
Highly unlikely. Tobacco use, including smokeless tobacco, is certainly a risk factor. Most patients present at over age 50. There may be few or no symptoms. Mouth cancers can present as non healing ulcers that can be painful. Rarely, there can be painless lymph node enlargement. Patients are staged by size of tumor and lymph node involvement.