Safe on 2nd, goes back to 1st

[SAWolf]

Hi,

Here is the clip:
http://mlb.mlb.com/video/play.jsp?co...y_26416825&v=3

Questions:
1. Isn't that a balk from the pitcher? (he did not break and he threw to an unoccupied base?)
2. Two runners on one base the following runner is out when only when tagged however if the preceding runner stepped off the base thinking he was out and got tagged first would the following runner be able to safely claim second?
3. The runner going back to one was just crazy, right?

One large mess, coming right up...