I noticed this seemingly extra skin on my neck (skin colored). It seems like a wart or skin tag or something. Is this normal? What shall I do? I'm 17.

Probably nothing. Probably nothing to worry about as far as being cancer. However at 17 you probably don't want skin tags or 'extra skin' on your neck. Your doctor can easily remove these type of spots in the office. It usually just takes a minute or two and doesn't generally leave a scar. If it appears concerning they can send it for evaluation.