Wow I had no idea that seeing flag desecration as protected free speech (which strict constructionist Anton Scalia agrees with), believing that unconditional free trade that is not dependent on human rights, and voting to allow airline pilots to carry guns are all considered "socialist." Sure, Sanders has some very socialistic tendencies, from believing in Canadian-style health care, supporting increased taxes for everyone, and demilitarization, but the overwhelming majorities of these votes suggest a more left of center positioning rather than a far left of center positioning. Essentially, he agrees with 75% of Democratic positions, while on the other 25% he goes a little further to the left.
As for "voting to organize" the Senate, that means that Sanders will be part of the Democratic caucus and on the first day of the Senate session, he will vote, along with other Democratic caucus members, to elect Harry Reid Majority Leader, Dick Durbin majority whip, and the whole slate of Democratic committee chairmen. So yeah, basically, when the Senate President asks who wants the Democrats to assume the position of majority party and organize the Senate, Bernie Sanders will say "me!!" Look at a government book, "organizing" the body is the shorthand term for this (AP government exam tomorrow; I've been studying up).