Answer 1

designers are involved with designing the look of a site which the developers then take and translate into functional code etc.

a basic understanding of math concepts helps. at least a minimum of how to manipulate equations. you never know when a web project will need some calculations. you don't need a degree in it or anything.

my last project required building graphs and calculating best fit trend lines for the data. needed to know how to do some math for that. I've worked on debt reduction calculators which needed interest calculations etc. so yes it comes in handy. Google is your friend for what you dont know but a basic understanding can't be googled.