Yes there are a few companies that make them. I'm not sure what they are, you'll have to search around a bit.
Look for a non-silicone polyester fibre for a low fire risk.
Childrensplace.co offers stain resistant clothing.
Yes, some duvets are treated to be stain resistant. Some are also treated to be anti-fungal, anti-bacterial, and have dust-mite protection.
Enameled metal tubs (steel or cast iron) are the most stain resistent tubs. Most tubs made today are very stain resistent as long as they are cared for properly. Abrasive cleaners that scratch the finish cause staining because dirt gets trapped in the tiny scratches and remains after cleaning.
There are some stain-resistant and wrinkle-resistant kids' clothes, but also consider getting a color that hides stains well such as green.
There are some, such as ones made from the same material as stain-resistant khakis, but they are expensive so be prepared to pay top dollar for them.
Most bedding sets are not stain resistant, unfortunately. The Pooh Come Out and Play set is one of them. The best advice is to arm yourself with stain removing detergents.
All of the popular baby bedding companies like Gerber and American Baby have stain-resistant/proof baby bedding. Just look for fleece sheets. Spit-up and milk will wipe right off!
Draper and Bedding is reputable and provides custom duvets.
Nautica Fiji Duvets are a great buy,and a value for the money.
There are duvets of such stature. You can search for them online or call your local furniture store to see if they carry them.
Yes, you can put a regular comforter in a duvets cover. Before purchasing either a comforter or a duvets cover, measure the item that you have and make sure that the comforter will fit the cover and vice versa.