the thin part of the cord wraps around those cord ears no? that's what it's there for no?
It's there to ruin your cord.
In theory it's a good idea for stowing the cord and the pack, but #1 it makes the pack thicker which in my experience fits
worse in a bag than it should, and #2 like any wire or coat hanger, if you bend it back and forth in the same exact place repeatedly you will cause metal fatigue and break the wire. Winding the cord around the sharp turns at the ears repeatedly in the same exact place is just asking for cord damage.
I have taken apart one of those cables that was damaged that way, and when I peeled off the white jacket, an area about 3/4" long at the bend where there should have been a continuous braid of wire, there was wire bits about 1mm long each, that fell onto the table like sand, leaving an exposed white insulator around the core wire, with no outer wire for almost an inch. The white insulator (plastic) was severely cracked at that same location. In this case the wire had become intermittent, having to be bent carefully to start charge. In other cases I've seen, the white insulator was breached at a crack, allowing bits of shredded shield cable to get in and touch the center conductor, causing a short, and either leading to sparks (rarely), or melted outer plastic jacket. (numerous examples) Thankfully no fires, but it was certainly a possibility. The new magsafes are much better protected against this because the white pack will stop sending power if it detects a short.
I never use my pack's ears. The pack in my bag I stow by carefully looping the long cord in about a 5" circle, finishing by folding the pack down into the middle of the loop and slip that into the bag. In this way the pack also doesn't get any thicker so it doesn't bulge out my bag quite so much. It goes in there beside a 2.5" lacie service drive and an airport express, which are all the same thickness, so there's no bulge at all in my bag on that side.
How much time do you get on a batter?
varies wildly on my use. when I know I'm going to be pushing it I'll turn my display intensity as far down as I can tolerate, make sure my computer is set to sleep the display, and sleep the computer after a short time. (5 min) A lot of the time I have to get my computer out for service, I'm only needing my computer for brief periods of time over what may be hours of work, so the computer gets to go to sleep or sleep the display a lot so battery life can effectively be 8 or more hours. But if I'm actively using it, like to say watch videos to kill time while waiting for a car repair, I can expect 1.5-2 hrs per battery. So it's very dependent on your use.