iOS 9 features don't work in iPad mini
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.