A6. "That depends…"
* GoPro - type can take pics/video on trips. Drawbacks and benefits, obviously.
* Phone. Hands down it is best price-for-quality instant-on device. Sorry, it just is. If you want geeky photo control, that is also possible with some devices using alternative software. You will need to do your research on that, though, before you buy.
A3. My limited use of AI to date is to point it at things that I have written about bikes and bike rides. I log my rides in Obsidian if they are notable and asked it to summarize.
I just did this, and it correctly inferred from a small hint that the Border to Border Trail here is a good place for easy paved miles - that is not something that should need gallons of water to infer, but it does mean that my written notes are consistent with experience.