Open URLs in Google Chrome and resize windows

Question 1

You can use JavaScript. Save the following code as a .html file:

<html>
<script>
function openWindows() {
  window1=window.open('http://google.com/','','width=400,height=300');
  window1.moveTo(0, 0);
  window2=window.open('http://yahoo.com/','','width=400,height=200');
  window2.moveTo(0, 300);
  window3=window.open('about:blank','','width=200,height=500');
  window3.moveTo(400, 0);
};
</script>
<button onclick="openWindows();">Open Windows</button>
</html>

Open it in your browser and click the button. You should see something like this:

Multiple popups

NB: You'll probably have to relax your popup blocker settings. Here's how to change the popup settings on Chrome:
Chrome popup settings
This won't change popup blocker settings for other websites.

On Mac, an extra monitor extends the screen size. For example, if your secondary monitor is arranged to the left of the primary monitor, window4.moveTo(-300, 0); should do the trick.

Question 2

Probably you're interested in open. So you could open /Applications/Google\ Chrome.app or you could similarly open http://www.google.com. You can also use AppleScript to position windows automatically, including directly from the command line via osascript — see e.g. this answer on the Linux & Unix StackExchange.