Red Bell Peppers and Cauliflower question

bazzaboo

I'm a first timer this year so its all new to me.
First question: I've got Red Bell Pepper plants and they have lots of peppers growing but are green! So will they turn red when they're ripe like tomatoes? Or can you eat the green ones too? Are the red ones just red because they're left on longer than the green ones or are they a totally different plant altogether? Also how big will they grow? Like supermarket sized ones? The plants are not even a foot high and I cant imagine the peppers being the size of supermarket ones.

second question: My cauliflowers have black bits on, they look like tiny eggs. What is it?

Thank you