How much time should be alloted to a college application?

I am starting the college application process in the fall and was curious to see how long it takes to complete a college application. Should I allot a few hours or a few days per application? And is it true that when you apply online, your SAT scores need to be sent by collegeboard and your letters of recommendation and your transcripts need to be sent directly from the school? So I would only be in charge of submitting my common app and essays? Then as the colleges receive my information they create a profile or a folder with all of my information and won't look at it until all parts have been received? I'm a little confused, any advice would be helpful!! :) Thank you!