If I have a lot of functions on startup do they all have to be under one single:
$(document).ready(function() {
or can I have multiple such
Yes, it's perfectly ok.but avoid doing it without a reason. For example I used it to declare global site rules seperately than indivual pages when my javascript files were generated dynamically but if you just keep doing it over and over it will make it hard to read.
Also you can not access some methods from another
jQuery(function(){});
call
so that's another reason you don't wanna do that.
With the old window.onload
though you will replace the old one every time you specified a function.