Yes, 100%. Rinzler clarified this edit on starwars.com, it’s all in the thread Dom posted.
It’s possible, but George contradicts himself so often in interviews that it is hard to say what he did or didn’t know early on in production. Like he says the films were always meant to outline the rise and fall of Vader, but is clear he didn’t plan for Vader to be Luke’s father until writing ESB. That’s okay, it is just not fair to fans to make them think he had it planned from the beginning when he didn’t.
Originally the Force came from crystals, and of these crystals was the MacGuffin for an early draft. I would say he was figuring out the Force as he went along.
Those beings at the end of the Clone Wars weren’t stated to be Whills, but Force priestesses. They may have been, but it was never clarified, which makes me think they weren’t.
If the Force is meant to be a faith-analogy, then I think the Force can be explored, but should always remain ambiguous and mysterious, even if it is a real thing. Even though it is a real energy field, you still have people who interpret it differently: the Jedi and Sith have to completely different philosophies on the function of the Force, and both would say the other doesn’t understand it. Then you have creatures like the Bendu who see themselves as in “the middle”. You could have people like Kreia, who see the Force as evil and wish to destroy it. Basically, the Force needs to be ambiguous enough for it to be open to interpretation, like how many real world religions interpret our own reality.