1. Different profiles possible ? need an buyer and an seller profile
Yes, you can create different profile types by using CB Conditional to show/hide other fields/tabs based off another fields value. So for example you'd have a Select or Radio field where they select what their profile type is then you'd show/hide other fields/tabs based off that selection. This then gives you different features throughout profile view, profile edit, and even registration based off that type.
2. search for zip code / country works ?
We don't have radius searching. That's something you'd have to code yourself. It's still possible to search zip code, but it'd just be exact searching. Same for country.
3. limit for messages possible ? so we do not want that an buyer can send unlimited messages to an seller if he is not registered.
There's access controls for messaging so you can limit who can message based off their Joomla usergroups. Anything beyond that you can use CB Auto Actions to implement custom limitations.
4. pay plugin ? : different packages possible for different profiles ?
Not entirely sure what you're asking. You mean a user pays and gets different features on their profile? Yes, that's possible with CB Paid Subscriptions.