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.
sure, at least when I order stuff from the US, I use USPS' priority mail service (I think it is one of the cheapest options), it kind of sucks because it takes a little longer for the packages to arrive, but the brazilian customs doesn't pay much attention to those packages. That probably happens because the volume of packages that come through it is a lot higher and the items generally have lower value (therefore, if you use high end services such as fedex, DHL, etc there is a pretty high chance that your item will be held). On top of that, the packages must be as "low key" as possible. The more they resemble regular letters, the less likely they are to be held. Last, but not least, in the customs form the items must be declared as "gift" with declared values in the range of 10-30 USD.