In my experience so far the recovery week workouts (in Build) haven’t been adjusted upwards by AT, at least not in the I think 2 recovery weeks I have had on my plan since being on AT - and nor should you do it manually really: if you think about it, why would you want to be doing e.g., Stretch workouts when you’re supposed to be recovering? As noted above some of the plans seem to have slightly different goals though, I see my next recovery week (in Specialty) has some harder looking workouts in it. So I would follow AT for now.
Only caveat is a lot of people seem to have better Endurance than their PL suggests simply because they’re doing most of their endurance work outside of TR (longer unstructured outdoor rides etc), which isn’t accounted for currently by AT. But even still, recovery workouts are supposed to be easy!
No - in general, just because a workout is rated Achievable it doesn’t mean you shouldn’t do it, it just means it should be achievable for you. My plan still has a number of Achievable workouts in it alongside the Productive/Stretch ones - you probably don’t want or need to be doing Productive or Stretch workouts every day! I also often pick Achievable ones if I am adding in extra workouts, on the basis that I want to make sure I can hit the scheduled harder workouts properly.