In reply to John.

You can access the full module list by going to this page in your dashboard:
https://yoursite.com/wp-admin/admin.php?page=jetpack_modules

still no visitors count in dashboard stats (only page views)

We haven't redesigned the built-in dashboard Stats yet, and that's indeed something where we have to work to do! Good news is, you can already get advanced stats in the WordPress.com dashboard and in the mobile and desktop apps.

what’s the meaning of this sentence: “Photon can now be used within the dashboard” – which dashboard and how is this done?

By default, Photon is only applied to images on your site's front-end, when readers are looking at your posts and pages. We've now added a new filter, jetpack_photon_admin_allow_image_downsize, allowing you to have Photon applied to images in your wp-admin dashboard as well. You can find out more about the filter and how to use it in our code reference.