2. And while screen burn in (or LCD "persistence") is still an occasional problem, under normal circumstances it shouldn't be an issue with something like this. You need to leave the monitor on for very extended periods of time with static screen elements in place for that to happen. I've only seen persistence occur (and that very rarely) on things like order entry kiosks, status boards, or other "ON-24/7" setups where the screen acts more as a control panel or entry keypad.
Yeah, I know modern screens shouldn't have much of a problem without them being on for a very long time (in the > 24 hour range, IIRC), but a screen saver's job is to save the screen, not rely on the user to set his monitor to shut off.
FWIW: I set my screensaver to come on in 15 minutes and my monitor to shut off after 30 in order avoid wasting electricity. So should most people. If you're getting screen burn from a screensaver on one of today's monitors, you're probably leaving it powered on way too long anyway. So save a few cents along with your monitor by taking advantage of available powersaver settings. It's good for your wallet - and good for our planet too!
FWIW: I think I have you beat. I've got the screensaver set to 10 minutes and to shut off the signal at 20 minutes. Though it doesn't actually cut power to the monitor. The LED still blinks as it waits for a signal to come through. And though I agree it's good advice to have settings similar to ours, I don't expect everybody to know it's possible, take the time, or even have the permissions (corporate PCs) to do it. Thus my insistence that screen savers do their job.