Learning different chineses

[nice gaijin]

What do you mean by very difficult? they will be able to get the meaning of what another is saying?

Not without an understanding of how the other dialect works. If they only understand their own dialect, communication is only possible through writing.

If they all have different tones, then how can they communicate at all?

The tones are not the only difference; the key words in Supervin's statement are "mutually unintelligible"

So SVO is they way english is spoken???

yes, SVO means subject-verb-object sentence structure.

If Cantonese has six to nine tones wouldnt they need more characters than mandarin and wu???

No, the characters mean the same thing, they are just pronounced differently.