предлагаю первое предложеие переделать так: Subculture is a group of people. They have the same interest and the same style of (clothers , sort of music, living).
all people - это множ.число поэтому - those all people.
People are in the group are not bad.- звучит не по англ, лучше будет так: I didn't think people being in the group is bad , they just want to change the world for the best.
It is very well to be/being(на твое усмотрение оба варианта верны) in a collective. we like to draaw THE attantion, and to achieve THE goals.
Со временами всё отлично вроде.