stan With how your post formatted I thought it was a poem at first, that would be a first for meatgistics!
Casings are up to you but I would recommend the 32mm hog casings or the 30 or 32mm collagen. Are you smoking this or no? If you are making a chicken Bratwurst then you dont need cure as bratwursts are just grilled or pan fried, if you are smoking it then you want to use the cure to help keep it safe during the smoking process.
Celery juice powder can be used instead of sure cure as it has curative properties and should be used at the ratio of 4 oz to 100 lb of meat, so .04 oz per lb.
Cold phosphate is 2 oz per 25 lb of meat so that would be .08 oz per lb of meat.
Carrot fiber is 4 oz per 25 lb to that would be.16 oz per lb of meat.
Now, if you use the cold phosphates and the carrot fiber I would recommend you go with 3 pints (which is 3 lb of water) of water per 25 lb batch. it might present a little soupy but more moisture will stay in the sausage.
Whether you are making a cured sausage or a true bratwurst I would recommend grinding the meat at least twice, the last time through a 1/8 plate and mixing it ery very thoroughly.
For the breakdown of how much of the seasoning and for cures and additives as well check the bottom of Seasonings Page as it has conversion charts for all 3 at the bottom.
Hope this helped!