Those ads are probably displayed by google's launcher, you can easily disable it from adb and use any other launcher you like. I personally use FLauncher, I love how simple it is, I don't need anything else
Same here, one other improvement I would recommend is remapping the Netflix button to something less annoying/more useful in case you press it accidentally. If you have Hue lights, you could make it toggle your lights with this app for example.
Hue Shortcuts - Apps on Google Play
Control your Philips Hue lights from your TV remote
Probably tracking, Spotify urls have included this for a while now.
The value seems to be different every time you share something so it must include a timestamp.