Charcuterie is a great book. We also have it. It looks like there are directions on the seasoning mix. The potassium nitrate is also known as cure #2, which is used for dry cured products that are cured for an extended period of time, versus cure #1, which is a mixture of salts used for very quick cures and/or cooked/smoked products. Do the instructions say anything about either of the cures? I can't quite see all of the ingredients. Yes, the cures can be dangerous, but you'd have to use quite a lot. They are dyed pink so you'll know the difference between them and table salt.
You have synthetic casings. We've never used them, but I don't believe there is any prep needed for them, other than maybe wetting or soaking for a very short time before placing them on the stuffing tube.
A dry cured sausage is weighed and then hung in an area where you can control temperature and humidity within certain ranges. We used a small wine refrigerator since we live in a hot and humid pretty much year round area. The sausage is weighed periodically to measure moisture loss. PH is measured somewhere along the way though I don't remember when as it's been so long.
