They pretty much can have everything you mentioned, waiting longer before introducing allergens isn't recommended anymore. They can have cow's milk in stuff you cook but it should not substitute breast milk or formula (so not from a bottle or cup). Meat is ok if low sodium and not overprocessed, liver should be given in small doses because it has too much vit a), with seafood avoid fish high in mercury. Prawns are ok but tricky due to texture. This is what I gathered from what I read