we do not share your data with anyone and there are many ways to control the visibility and storage life of your data here.
but the internet is a public space and you should always assume your data could be compromised.
be smart with your password, use tor or a vpn, and use pgp for sensitive communications.
This depends on how you use them at home/mobile and what operating systems you will connect to. For instance mobile would be jabra or apple, neither of these are choices for listening in cans at home or the office.