Thank you for explaining!
I had never seen red skin like that before (or a battle trimmed one), so it may very well be from the treatment you describe and not parasites... geeze, what kind of parasite could withstand that.
Do you know if it makes the feathers not grow back in the next season or just for looks (rather heat) and has to be done each year?
Very often if a bird is molting you will see new pin feathers coming in, like the tail area where you are concerned.
Sounds like you are going to be taking good care of him. And as saaniya said, my birds also have lots of mini molts on their way to maturity to grow in their adult plumage.
Since the red skin is not an indicator, in THIS case of parasites... checking after dark with a flashlight and parting feathers down to the skin and look for things running away will give you a best picture when you do need to check them... as things are surprisingly hard to see during the daytime.