The [Bellman-Ford algorithm][1] determines the shortest path from a source $s$ to all other vertices. Initially the distance between $s$ and all other vertices is set to $\infty$. Then the shortest path from $s$ to each vertex is computed; this goes on for $|V|-1$ iterations. My questions are:

 - Why does there need to be $|V|-1$ iterations?
 - Would it matter if I checked the edges in a different order? 
 Say, if I first check edges 1,2,3, but then on the second iteration I check 2,3,1. 

MIT Prof. Eric said the order didn't matter, but this confuses me: wouldn't the algorithm incorrectly update a node based on edge $x_2$ if its value was dependent on the edge $x_1$ but $x_1$ is updated after $x_2$?


 [1]: http://en.wikipedia.org/wiki/Bellman%E2%80%93Ford_algorithm