These are the main things the 8 has over the SE:

• Faster performance
• Blood oxygen and ECG sensors
• Always on display

You can actually compare all models still sold by Apple on their website.

Apple Watch upgrades are very incremental. If you buy a new one you'll very likely get software updates for longer. So I'd buy the cheapest new one you want too afford.

The always on display may not be necessary. It's mostly useful for glancing at the watch without touching it before.

Well, how do you proof an email has been delivered if you don't get a confirmation? That's the main problem when going to court.

The settings icon on the profile page is maybe redundant now but hardly a massive issue

I'd say, the settings icon should stay on the profile page and the tab bar should be used for some other feature. I don't change my settings so frequently that they would warrant such a prominent place.

Those were popup windows years ago and every browser started blocking them and does to this day. I wish they would start blocking overlays too.