Your pack should have appeared in the left window, just hover over it and click on the arrow pointing to the right.
zip file you downloaded in the first step to the newly opened "resourcepacks" folder. – folder titled "resourcepacks" will pop up
Players just pick their skin of choice, and that’s what they look like – every time, in every world unless skins are disabled on a particular server. Character creation has never really been a thing in Minecraft.