I never measure my spices so I can't help you there. As far as meat goes I'd count on between 1/4 to 1/2 lb per person. I frequently make large amounts of chili for a homeless shelter and we feed about 50. I usually start with about 20-25 lbs of ground beef. Sometimes I'll cut back on the beef and make up the rest in sausage. We usually have enough so people can get seconds and then they can eat until they are full or it is gone. We usually have some left over but not much. For serving 25 I'd probably start with 10 lbs of beef and 2-3 lbs bulk sausage. Once you get everything mixed together, start adding your spices. I just dump it in and taste. You'll want to use chili powder, paprika, maybe some cumin, and I use seasoned salt and pepper. Just add it and taste until you get the flavor you want.