1. In Polish language a double confirmation often means a negation. If somebody says "yes, yes", or "alright, alright" it does not really mean they agree with us; just the contrary - they deprecate what we say because they think they know better.
  2. 'We'll stay in touch' - that's what your Polish friend said but the phone is quiet. When Polish people say 'We'll stay in touch' it does not really mean that they are planning to call. 'We'll stay in touch' is a non-committal way of ending a conversation. That's it. Don't wait for the phone call.
  3. Your Polish friend lost his job? Failed an exam? Don't say "What a shame!" In a Polish language "What a shame!" is an ironic statement. Say "I'm very sorry" instead and forget about the shame :)