some differences between the way Americans and Australians speak

Through watching many youtube videos I've noticed some differences in word use between Australians and Americans. 

One of the differences is the use of the word 'whenever'. Americans use that word to refer to specific times, whereas we use it mainly to refer to events that happen regularly or events that we're unsure when they will happen. For example, an American might say, 'Whenever I first started reading War and Peace.....' which to me, doesn't make sense. There was a particular point in time that you started reading the book, so you would say 'when I started reading War and Peace.....'. 

Another difference is that we use the word 'of' more. Like, for example, I would say, 'a couple of people were walking down the street', where an American would probably leave the word 'of' out and say 'a couple people'. Or.....'in a couple of months I will start a new job' vs 'in a couple months I will start a new job'.