Welcome!
Not sure about the first question as I don’t use Train Now. I think it handles TR workouts but not others. I believe it just looks at history not what’s coming up but those who use it might confirm or refute.
Plan Builder is sort of “fire and forget”, once you’ve gone through the steps of creating a plan it’s up to you to manage it. So if you need a week off for illness, holiday or recovery then you have to modify the plan yourself. This is partly what Adaptive Training - AT - is aimed at, it looks at everything (well that it knows about) and makes adjustments on the fly so, ideally, you get the most suitable workout.