No, there are simply too many. Even gold has an E number (175).

People with allergies do remember the specific E numbers they have to watch out for.

The packaging often states what the E numbers are, either specifically or the general category (stabilizer, emulsifier, preservative, colouring, taste additive, ...).

http://en.wikipedia.org/wiki/E_number

Nope, but E150 is pretty well known because it is ... everywhere. But we do know that if whatever you buy has to many E numbers on its label its probably something you do not want to eat (That's a rule of thumb: Everything, even water, has a E number, but companies usually only put them on the labels for the not-so-nice stuff)

Probably just as many as Americans who memorize what Red #40 is.

Americans don't have to memorize it, they see Red and know it's a color.

Not really, but people who care about that sort of thing often know the handful they are most worried about.

I know E150 but nothing else.

Plus yellow #5. Thanks to eminem.