(ii) When writing a message, hold the "Shift" key while you click on the Compose Mail, Reply, Reply All or Forward links and you'll get a new window for your new message. (Holding the "Shift" key while typing the keyboard shortcut — in other words typing "C" "R" or "F" — has the same effect.)
(iii) When reading a mail, hold the "Shift" key while you click on a message to open the conversation in a new window. (Same effect for the "Shift" key and the "o" or "Enter" shortcuts.)
Unfortunately, these tips don't work in Internet Explorer, so to see the speed-up, you'll need to be using Mozilla Firefox, Apple's Safari, or Google Chrome.