It means REPOST 你的微博名字是什么？我们可以互相关注一下 ：）

same as cc

it means share something to your weibo page(a Chinese social network service similar to twitter) just like share something to facebook

谢谢！

that means someone has reposted the picture or words you had posted. when they just repost without giving any comment, these words--“转发微博” will be systematically posted.