@liquidburn The implementation and billing is quite confusing and things will undoubtedly change multiple times. For now, here is what some testing with my team has shown in regards to your 2 main questions (apologies if all it does is add more confusion):
The Teams subscription is a standalone product and has some increased functionality over Plus plans, but lacks other functionality that Plus plans have. So, if you and your example friend want to use only the workspace account, you can do that. However, if you cancel the “Personal Plus” account, you will not be able to create a builder profile, verify it, link it to a website or provide a privacy policy. Although the GPTs that are created under the Workspace account can be shared publicly, none of the builder profile settings are (currently) available in Workspace.
A feedback feature was added to the builder profile section that allows developers to get feedback from users. However, because of the above, it makes it problematic for a business to take advantage of the feature.
Also, while the announcement may be confusing/misleading, you are actually able to share GPTs within workspace as outlined in the announcement details. However, the ability to control WHAT is shared is only available to Enterprise customers (150 seats and up).
No, the chats are not visible by other team members until you share them with each other. However, due to recent changes to the sharing features (specifically deprecating picking up where another team member left off) this sharing functionality has been reduced to simply giving a team member something to read.
You can get more details on sharing here:
https://help.openai.com/en/articles/8474715-chatgpt-enterprise-shared-links-faq
I hope this helps and provides SOME clarity. Expect everything to be different tomorrow though. 