Many high quality duvet covers come with ties inside the corners. You use the duvet cover ties to loop through the corner tabs on the duvet/comforter. It's a nice feature that keeps the duvet/comforter from sliding around inside the duvet cover.
I m not sure of dimensions because they went to a private mountain vacation rental. The queen comforter on queen size bed was plenty ample in size; light weight but very warm and cozy. It probably dropped down approximately 10" on each side For the price I paid I was amazed!!! When needed will purchase others from Amazon.
Mine is slightly heavier then a lighter duvet. It is one whole blanket not a duvet. The whole thing does fit in my stackable washer. It is a little warmer during the summer. It’s very soft and light in weight.