Answer to Question 1
Red would probably be a good color choice because in China it signifies joy and festive occasions.
Since white is a color of death and mourning in Japan, it likely is not often used for wedding garments there.
Specific countries named will vary, but the site indicates that individuals from climates with less sunlight (e.g., Canada, Norway) prefer cooler, less saturated colors.
Answer to Question 2
True childrens wear fashions began to be developed in the late 18th and early 19th centuries, partly as a result of the more enlightened views of child rearing and childhood advocated by philosophers such as Locke and Rousseau.
The Industrial Revolution gave rise to a large middle class eager to show off its newfound status. Consequently, children were again dressed not for comfort but to indicate the social position of their parents.