What is a 6'4 beat?
Traditionally 6/4 is meant for when you have two big groups of three per measure (ONE - two - three - FOUR - five - six), but this grouping could also be covered by 6/8. So you really only use 6/4 when you want to emphasize the broadness of the the beat values.
What is the strumming pattern of Wonderwall?
Having the pauses in the right place is just as importent as the correct strum pattern. As for this being an easy song, yes it is as apart from a 'D/F#' in the pre-chorus, pinky and ring stay the 3rd frets of high E and B strings.