My understanding is that you cannot access the standard debian desktop (or even a terminal) from the id. Given that, there is no browser or ability to install one (or apps for that matter).
In that sense, the id is great for local media playback (especially via Panel or one of the other "remote" apps) but not great for streaming playback or external purposes.
As I understand the state of play and based on my experience, I'd agree that it's true that a TTY / SSH session is not available with an Id. However, you can access a restricted Debian OS desktop (access to functions outside the MC software are limited). This GUI is handy for initial setup and configuration of the Id before reducing down to headless mode. The user has the option to access the desktop via a remote session.
To answer larryup's questions (again based on experience / personal understanding):
Can, as examples, Netflix/Amazon/Spotify apps be installed from the internet or be run from a browser?
... that's a no for app installation (unless I've missed something). Via a browser - different story - it might be possible but I'll defer to others for detail. See my points relating to browsing below.
can [you] do things like use a stand alone browser, email application (like GMail) browse a news site, etc?
... sort of - MC is equipped with a browser integral to it. So, browsing and sending email from a web client can be done but the experience will probably be "clunky" for most users.
This functionality is not a primary mission objective for the software, so I would suggest that user expectation be moderated with that understanding.
Does it have a wireless access point installed, or does the user need to provide one if wireless is desired?
I've used an Id (non-Intel NUC based) accessing it via WiFi via a router based network. I don't believe it has the function of providing an access point / WiFi hotspot.
The above is what I've experienced or understand. Happy to be enlightened if I've misunderstood. The software could also have been improved and I missed the key detail in a published change log.
All the best.