2) "Heart -> Mind -> :Ki: -> Body" vs "Mind and Body unified":
I'm not qualified to tell which is better. To me, they're two different training methodologies.
I think they're the same thing. The idea and translation indicating "mind and body unified" is not uncommon from a traditional Chinese standpoint either, and since the ki logic, how it works, etc., is pretty immutable, I can't see any way for there to be two separate things that are talked about with the same terms that coincidentally come from the same background.
In terms of the spiritual and quasi-spiritual attributions of qi/ki, god, universe, spiritual, etc., you certainly have to know that such discussions are not uncommon in Chinese (as indicated in your post), but many of those aspects are subjective and tangential to the function ki/qi skills. Regardless of whether one believes that ki/qi is a physical manifestation (as Tohei indicated in the Hawaii interview on Aikido Journal) or whether it is a spiritual manifestation (as O-Sensei and others have believed at various times in Asia, in different countries), one still has to be able to demonstrate the skills in order to achieve the effects. For instance, O-Sensei doing one of the ki demonstrations (let's say one of the many "immovable" ones) had to use physical skills to demonstrate a physical effect. Whether he was doing it in a "spiritual" way or not, there were measurable forces at play. If there are measurable forces at play, the discussion about it being the product of "love", etc., becomes moot, logicially.
Good post, though, Ting.