The Nats will beat Algeria tomorrow, along with a German defeat of Ghana. This likely puts the US as number 1 in the group (England won't beat Slovenia by 2 more goals than the US will beat Algeria). US then plays Serbia in the round of 16 (Serbia won't lose to Australia). The winner of this match faces the winner of South Korea-Uruguay to advance to the semi-finals. Certainly we could lose to any team in South Africa...but if someone would have told you two weeks ago that on June 22 we would be undefeated and all we need to do is beat Algeria, Serbia, and Uruguay/S. Korea to make the semi-finals who would have been happy?
For England to be first they need better goal differential. That means a 1x0 win by the US and a 2x0 win by England put England first. The 2-goal difference that has been talked about comes into play if both teams tie. If both teams win it comes into play if goal difference is the same and England scores two more (eg, US 1x0, England 3x2) in which case The US has a goal difference of one and 4 Goals for, 3 against and England has the exact same stats. Anyways, for the US to win the group they just need a better margin than England, the two goal difference would produce a tie that would be broken by drawing lots.
The odds of these wins average around 40% (complete estimate). So the odds of all of these games turning out the way you predict as easy wins is 0.4^5. 1.12%