First welcome aboard Longhaul.
Next I can help, throw away the Kutas book.......
Go get The Stanley Marianski book.https://www.amazon.com/Home-Production- ... ey+sausage
The Kutas book is misleading in that it is self serving to sell their products other than that it is OK but a first timer does not know enough to read between the lines and extract the good information.
Two examples "Insta Cure" is simply the government approved curing salt #1 usually referred to as "Pink salt" available from many places "Insta cure" is only sold by Kutas. BTW it is exactly the same as Cure#1 that is regulated by the government.
Fermento is of course another Kutas product that although they lead you to believe it is a bacterial fermentation starter it is not, probably has ingredients to lower Ph to mimic fermenting.
The Marianski book is the real deal straight forward information to guide you to your meat processing goal.
Actually Marianski has several books but the one I've listed is the best for your purposes.
To answer your question yes you can use cure #1 at the rate of 1 teaspoon per 5 lb of meat when making sausage no need to bother with the fermento or cultures.
Actually fermented sausage is quite different and should be addressed separately in that it needs to be dried in a humidity controlled environment but the Marianski book covers that.
May Rytek Kutas RIP and may you have a rewarding journey into the sausage making world.