iOS – No New Wallpapers in iOS 10

Apple maintained support for all iOS 8 devices in iOS 9 but that meant that some devices couldn't fully support some of the new features. If it's the first generation iPad mini you have, drawing in Notes is not supported. Support starts with the iPad mini 2.

I haven't seen anything about Siri Suggestions not being supported. You could verify that your device is supported and Siri Suggestions are turned on under Settings > General > Spotlight Search. There should be a toggle for Siri Suggestions if supported.

Yes. Nearly every iOS update phases out some of the wallpapers and introduces new ones. They typically phase out the oldest wallpapers while adding new ones into the mix. Many of the earlier iOS versions introduced and phased out fewer images, but the last few have introduced more, and subsequently removed more.

The dynamic wallpapers have stayed the same since they were introduced in iOS 7.