I'm 21, and no, I don't have any chest hair. But since you were wondering, I have no trouble growing pubes.
the difference between v-necks and their acceptabilty in culture:
DO NOT EVER WEAR THIS, YOU ARE A HOMO
a simple v neck is perfectly acceptable. when it goes to the length of that picture above^^ then you have crossed the line into unacceptability.
lower case v = OK
upper case V = NOT OK