I pre wash everything except thread lol! That said, I take the batting out and put it in hot water in my top loader, some soap, let it soak overnight. Then I drain and let it spin out. After that I put it in the dryer on high heat. So far it has all turned out just fine. Some things are fine for the crinkly look, some I don't want that. I don't do a rinse cycle on it because after I finish with a project I wash them anyway.

Read what the manufacturer says on the packaging.

I have never washed my batting because when I am finished with the quilt, I have to wash it to remove the starch and Elmers school glue I used during construction. Bonus, I love the change in a quilt when it "blooms" from the washing and drying, but that just seems to be me...

Maybe treat it like I do my tweed/wool. I don't want to have to dry clean all of my garments but if they are shrunk before making they will later. I instead of steam press them and you can also have the dry cleaners do this. it has to be done with steam or it won't shrink.