1. normally it's safe, but will often be fake, oscypek should be made from goat milk, while most of what you can buy from those people, will be made from cow milk and won't have the characteristic taste.
it's cheese, from the hygiene point of view it should be safe
2. no, the bottle includes something that's called "żur", it's sort of mild acid - the main ingredient of the soup, not ready for serving yet. you use it like vegetables in a vegetable soup

whatever you add to the soup, sausage, egg... will be "correct"