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.
It's super easy, when you are asked to make a payment you are given an address. From your bitcoin account just enter this address and the amount you want to send, it's usually received in less than a minute anywhere in the world.