YouTube is one of the best sites on the net, as there is a wealth of useful information there.
It's also the most dangerous site on the net because anyone with a web cam but without a clue can post a video.
Skip the videos and keep asking questions here, where you have a large group of experienced winemakers who are well versed in helping people. More importantly, we cross check each other so you'll get solid information. Everyone who has responded to this thread (posting or clicking Like) is an experienced winemaker whose opinions are solid.
However, keep in mind that there are diametrically opposed schools of thought in winemaking that are all perfectly valid. I suggest you pay attention to "why" someone does what they do, as that will help you make decisions.
On to your questions:
I do not apply heat to wine. Heat + fruit = activated pectin, which is to be avoided. I don't pasteurize wine either. You're adding K-meta (Campden) while is anti-microbial and using commercial yeast, which is cultured for properties such as stomping out the competition.
Regarding sugar, 1 lb (2-1/4 cups) sugar dissolved in 1 US gallon of water produces SG 1.045. Mix your fruit and water, and stir it well. Take an SG reading and subtract that from your target SG. For instance if your must's SG is 1.045 and your target is 1.090, adding 1 lb sugar per gallon should hit your target. I suggest you put in a bit less than you think you need, then stir VERY well. Then stir it again (nope, not joking). Then take an SG reading and add more sugar if necessary. Keep in mind that it's a lot easier to add more sugar than to take some out ...
Add 1 Campden, WELL crushed, per gallon, plus pectic enzyme. Let it rest overnight with a towel over the bucket.
I suggest making an overnight starter (
https://wine.bkfazekas.com/how-to-make-a-yeast-starter/). In the morning, stir the must again and re-check the SG. Adjust the SG if necessary.
Then add nutrient and the starter. I don't normally use energizer, but it doesn't hurt to use it.
Sorbate? DO NOT add it now. Sorbate + K-meta = birth control for yeast, used to prevent a renewed fermentation in the bottle. If you are backsweetening the wine, sorbate is added at backsweetening time, which is near or at bottling time, which is months from now.