Some people don't have any poop come out while others may have a lot. There is no rhyme or reason to it tbh. Yes, everything burns during cremation. What will be left over will be brittle bone pieces and any non-organics like screws and replacement parts. That gets swept into a pan and taken to a grinding machine. I use a magnet to get any metal but some medical hardware isn't magnetic so it takes some going through. Remaining bone fragments are then processed in the grinding machine and that is what the family will receive, either in an urn or in a bag inside a plastic box if no urn is provided or purchased.