Mandarin shares the same proverb. In fact, I find
Cantonese which is close to Mandarin much more easier to pick up
than other dialects.
My cantonese friend that they were choosing between Cantonese
and Mandarin to be the official dialect/language for China, is this
true?
1st part: It just happens that the proverbs were borrowed
from Northern Mandarin dialects into Cantonese thus the similarity.
Regarding phonology, Cantonese indeed has a closer
correspondence to Mandarin than Hokkien, Teochew, Hainanese and
Foochow. How about Hakka? Hakka has even closer
correspondence to Mandarin so should be easier to pick up for
you.
2nd part: I always hear about that. Whether it (really
happened in the past) is rumour or not, actually i dunno cos i
never check hehe