I would definitely pre cook the rice to 85/90% done. I would also precook the chicken, sausage abd rabbit(if having it) and add the shellfish, squid and fish at the end of the cooking. I’m a big fan of smoked paprika in my paella as well as a dominant yet not overbearing saffron flavor. I tend to toss in some gratuitous who herbs as well in the end for the aroma. That big of a group I would do two batches in separate pans.