It represents that it is a trending topic (or that people are attempting to make it a trending topic)
The @ symbol you mean? If you want to tag them in it, yes.
Tosho is a user on Twitter.
It is no longer in existence or is not mentioned about anymore or as much as it was before it's state of being "dead".
RTMI officially on twitter means ReTweetMyIsh
Where Will You Be At.
do you mean his address for twitter ? his twitter is @STEFANABINGDON
It mean Sunday follow .....
It refers to the Twitter PT Challenge. See the related link.
The location on twitter is usually the place where the page's holder lives.
It refers to a Twitter application to upload music.
retweet
Background.