A few thoughts…
Anchoring tends to be a trade-off between positional awareness and stability vs mobility. Contact only between forearm and guitar body works better if your sitting down rather than jumping around a stage. The forearm is fleshy, and you can probably track across 6 strings without sliding it. Just the movement of skin and flesh. That makes positional awareness more difficult than anchoring the wrist/palm areas on the bridge or body. Robert Fripp who teaches the wrist floating method, and is into various forms of ‘disciplinary’ practice admitted it’s difficult and takes a couple of years (I think he said) to get it working well. Every time the pick contacts the strings, there’s a reaction and it’s nice to know where you are afterwards.
Depends also on what you’re playing at the time. If you’re playing a lot of fast lines, then you probably know where the strings are just then; not far from where you last found them. However, if you’re performing with Hanz Zimmer, and the orchestra and audience are sitting in silent anticipation for your first pristine notes of a famous theme, you’ll probably be grateful for any clues as to exactly where the strings are.
It’s very common for people to drape their fingers across the body of the guitar. Lots of ‘Gypsy’ players do it, Petrucci, Govan, TG. On the other hand (npi), McLaughlin, Di meola, Gilbert, don’t. Dominant upward pick slanters probably tend to do it less because of the hand position.
As for curling the fingers, making fists, extending fingers etc. I think that’s getting more into the area of personal biomechanics. Some people’s wrists respond better to certain positions. McLaughlin commented on the hand needing to be not tense, but not completely relaxed. Which makes sense because wrist movements basically come from forearm muscles pulling on the hand bones, and so a certain ‘tone’ in the hand muscles helps give something solid to pull on. But it can be quite individual.
Best thing is to experiment so as not to exclude anything useful. Probably, the more varied your repertoire, the more you’ll do different things.