Can someone post a link 또는 an 기사 on 팬팝 that contains illegal sites 또는 anyway such things? Will they 신고 him for that, 또는 will he be banned from Fanpop?

it really depends on how illegal it is i suppose.
most users will 신고 the link/article/image/video that is posted, and if the main 팬팝 guys find out about it 당신 will be banned from the site probably.
if 당신 read the terms and conditions it speaks about this sort of thing, like breaching copyright.
당신 could look at the link 또는 the link for 더 많이 information.