Hello and Merry Christmas. It was very good to count on you in 2004. I hope we can keep in touch in the following year.
I only have one question. I've read some books with : How much time and others which show: How long.
Which is more correct? I mean, is there any difference between American English or British one?
'How long' is more common. I'd use 'how much time' as a more emphatic form. I wouldn't say 'how much time does the film last?', but I could say 'how much time do you need?' when trying to make an arrangement.