California has a new primary date

Ever since I can remember, the California Presidential Primary Election was always held in early June.

This year, it will be March 3, 2020.

This week, we got our "Official Voter Information Guide" from the California Secretary of State, which is the office that operates state elections.

The guide was rather confusing, because there was next to no voter information in it!

From what I can gather, the March 3 election will have two items on the ballot:

1. Select your preferred presidential candidate (from some list not yet known, or at least not contained in the Official Voter Information Guide)
2. Vote on Proposition 13. This turns out to be most of what is contained in the Official Voter Information Guide. Proposition 13 is a bond authorization measure, put on the ballot by the California State Legislature.

The Official Voter Information Guide also contained a number of pages about the 2020 Census, and refers you to http://californiacensus.org, which is a somewhat operational website with some cursory information. I'm not sure why the Secretary of State didn't refer us to https://census.ca.gov/ instead; that seems like a much better website.

Which exact list of presidential candidates will be on the March 3 ballot?

Will there be a separate election in early June, for issues other than the Presidential Primary Election?

How did this proposition come to be numbered 13? How are propositions numbered, anyway?

What is californiacensus.org and how is it related to census.ca.gov?

Oh, I'm just full of questions, aren't I?