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.
You should have an option to choose the currency amount like £50, or have the choice to buy part of a coin I.e. 0.001 bitcoin.