A rule of thumb for yeast re cider is:
S-04 finishes sweeter
Champagne finishes dry
Cotes-de-blanc finishes in the middle
Nottingham and S-05 are known to finish drier than S-04.
Here's a link to Papper's pasteurizing thread:
https://www.homebrewtalk.com/f32/easy-stove-top-pasteurizing-pics-193295/
Backsweetening, like many things, is a question of personal taste. We use just under 1/2 cup of Splenda for 5 gals cider, but others swear by Stevia, and some use lactose. Being lactose intolerant, cheap, and having been given a big bag of Splenda, that's what we use. You can incrementally sweeten and taste a glass of finished cider to see the level of sweetness you prefer, and then do the math so see how much to add to a full batch at bottling.
Also, don't be afraid to pick up a 1 gal glass carboy filled with Apple Cider or Apple Juice from the supermarket. You can drink or ferment the juice, then keep the carboy to use for small batch brewing to see which way you prefer, then do a full batch of that. Don't forget to pick up the right size stopper and a new airlock for each.
We love the 1gal carboys, because we can do a small batch for special occasions/holidays (e.g., 1 with a cinammon stick, 1 with some cranberry juice, 1 with some cherry juice, etc.).
My cider w/store-bought juice, no added sugar, S-04, plus nutrient and pectic enzyme went Godzilla on me from day one. Even after 3 weeks, I could see a stream of bubbles rushing up the sides of the carboy. After 3 weeks it was down to 1.010, so we waited another week to bottle. It finished around 1.007.