Yes, it attaches to a bike, and yes you could easily haul stuff in it. The arm is swiveled under the trailer, you can see the pin that holds it in place. The front wheel is removable.

I took an older, less fancy (smaller wheels, no brakes) InStep trailer I had used to haul my kids around when they were tiny, gutted it, added some scrap wood, and voila...



The brake on the one you linked would actually come in handy, I would think-- when mine has 60-70lbs of stuff in it, I can feel it developing a mind of it's own when going down hills. Just detach the brake from the handle at the back of the trailer and put it on a quick-mount on your bike.