I see you have several questions.
I will try to reply them all here, it may though be necessary to split this up into several tickets if we cannot clarify it all at once 🙂
1. There is (strictly speaking) only one way to set up post relationships with Toolset:
- by Post Relationships
The "post-reference field" is exactly as you describe it, a field where you can pick from a list of Posts (set previously in the fields settings)
It had been requested several times in past, to allow to connect one post to another one (of either same or another type), without the need to set up a whole relationship, and allowing to cross-reference.
It is not a "Post Relationship" as the one in Post Relationships section, it is a post reference feature.
The parent-child hierarchy is a pure WordPress feature, which is natively added to pages post type already.
With Toolset, you can just as well have this on Post Types, but it is a hierarchical and WordPress based relationship.
Repeating field groups are once more something else, those are Fields, that you need to be repeated on a single post, but it's a set of fields.
It's an entire repeating group of Fields.
This is not a post-relationship, but how you add Repeating Groups of Custom Fields to Posts.
2. None. Intermediary Post Fields cannot yet be displayed, as Christian already informed you here:
https://toolset.com/forums/topic/types-views-beta/
3. I do not understand this question, and it seems rather a large topic, I suggest to ask us this in a new, dedicated ticket so we can help adequately.
4. You cannot do this.
Only taxonomy views and archives can display the taxonomy term meta fields.
This is elaborated here:
https://toolset.com/documentation/user-guides/displaying-wordpress-term-fields/
5. Not that I know of, but I am also not sure what you try to achieve with it.
There is no plugin that will integrate Google Drive and Toolset somehow.
But maybe there are plugins that integrate WordPress and Google Drive:
hidden link
Although the possible applications here are countless, hence I cannot recommend a particular one yet.