Cold or warm water won't do the trick. Down with down. Comforters may look lovely in the catalogs, but they can wreak havoc with your respiratory system. Stay away from all items containing down or feathers. Choose wood over carpeting.
Wood floors are a lot easier to clean and to keep clean.
Always keep the floors clear so you can dust and vacuum easily. Move your clothing out. Clothing collects dust, too. If possible keep all clothing in a closet or dressing room apart from the bedroom area. Invest in an air conditioner.