Precook or raw sausage goes into the bird?
Recipes I have seen say precook the sausage, however didn’t we used to cook it in the bird as the bird cooks? Is this something new, or did we always precook it?
I’m pretty sure we always pre-cook sausage for stuffing. You want to render the fat, to brown other vegetables before we add it to stuffing. And yes, we really can’t trust that the bird cavity will get the very center of the sausage stuffing to temp. But you do want the Malliard reaction to add flavor.
Either from an abundance of caution or because birds used to be overcooked in the past, putting stuffing into a bird is becoming less of a “best practice”. So if you absolutely must stuff the bird with stuffing (vs. aromatics only), pre-cook the raw ingredients like sausage.
That said, Ina still stuffs her turkey and Alton recommends you do not. Go with whatever you prefer but make sure the internal temp of the stuffing is high enough to cook it through because it also will contain the initially raw juices of the bird.
I cook the stuffing completely separately. It really affects the time needed to properly cook the bird and I’m never sure how much extra to cook it. So I cook it separate to be safe. 
Precook all stuffing ingredients, then in the bird it goes.
I’m willing to risk the food poisoning for the flavors that are added during the cooking… and the opportunity to steal the crunchy bits off as the bird rests.