I guess I'll just jump in here for the last point.
I definitely agree with Professor Dubois about the dangers of being able to link a phone number, say, to other datasets, because most people do connect their mobile to their Facebook profiles and other social media platforms. There is a real danger there that then you're starting to get more than just the phone number and basic contact information.
I think this does get to the root of one of the big problems we want to address here, and that is the kinds of data political parties should be allowed to use in the first place when they're campaigning and reaching out to voters. Then, what are the limits to that data? I think once we can come up with good answers to those questions, enforce them and create more transparency around this data that political parties have between them and the voters, then that will be a win for democracy.