Can I have my cursor on at the end of the URL instead of selecting all of it, when I focus on the URL bar?

yup. either works. also clicking a second time puts the text input cursor at the site of the last click. click fast enough for a 'double click' will select the word or whatever windows thinks is a 'word' nearest to the double click.

also F6 or CTRL-L will put the focus up there without having to click. saving the mouse from making the (potentially long) journey there. then END or RIGHT puts the mouse at the end of the address. a programmable keyboard or utility, or autohotkey, could be used to make a new custom shortcut that hits those two keys with one keypress or alternate mouse button click.

the reason for the default behaviour is because the most common (and overwhelmingly so) things people do when they click or give focus to the urlbar is either copy its contents to the clipboard, or replace it entirely by pasting or immediately typing. these things require the entire url address to be selected upon focus.