1-- No, nor the structure. 2-- Yes. 3-- It is not a formal context, and I wouldn't use the colon; I'd use an m-dash and avoid that problem.
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Mister MicawberThe second 'sentence' of the former is a common spoken version: the question is asked and then the reason is given. You cannot represent that in a single sentence as in the 2nd. 'Because..what time' makes no sense.