Maybe... But why hasn't it happened then to any other words? I hope dictionarues wouldn't consider people's mistakes as correct langage-transformations.
Yes, but the uncreasing use of some words that maybe weren't in any dictionary makes them appear in a dictionary. The use creates the existence and the recognition.
Well, as far as I know, - to enrol and enrolment are rather used in the UK and the Commonwealth (Australia, Canada, ...) - to enroll and enrollment in the USA.
But you can use enrol in US English, too, but it's not so common. So, it's your choice, choose what you like best.