First, I don't have 15.1 installed as I don't install beta's on my primary devices and my M1 MBP is the only supported Mac I have for AI. I would first request to make sure 15.1 is indeed installed. You never know, it's part of that never assume a computer is plugged in part. I would then state that in Settings you should see an option for, "Apple Intelligence & Siri". There is a toggle to turn it on but from what I hear, there is a waitlist to be able to start installing the AI part. Not sure how the waitlist works but don't expect it right away I suppose.

https://support.apple.com/en-us/HT210904

I don't think it would be worth it. Based on what they said in the keynote, it will probably have a price tag with it at some point. It sounds like it's geared more towards a team of devs. The documentation is below. Xcode Cloud

The basics of course. I’m not sold on ARM macs but it’s definitely possible. AirTags could show up later in the keynote, maybe the last announcement. Disappointed in the latest MacBook Pro updates. They are mobility devices so WiFi 6 should have been put in them already. Especially with iPhone and iPad done. Apple TV is not needed really since it’s not meant to be mobile. I do have one of them on WiFi but thats only because my apartment isn’t hardwired for ethernet. We of course don’t know why Apple hasn’t put WiFi 6 in the MacBooks yet but hopefully soon. It was easy to upgrade my windows laptop with a WiFi 6 card. I won’t be able to upgrade until than. I would bet they will mention something about the current events going on in the states at the moment towards the start.