Welcome to the Wefugees community and thank you for your question.
1) I assume that you lost your refugee protection status issued by Costa Rica once you returned home, right? So you aren't holding some sort of document that allows you to stay in Costa Rica (or any other country) as a refugee at the moment? As long as you aren't given protection by any other state (or holding a visa etc.), BAMF is obliged to process your asylum claim.
2) In Europe we have the so-called Dublin III regulation. It states that there is only one country that is responsible to process someone's asylum case. Usually it's the country where you first entered EU, respectively where you get registered as an asylum seeker. After having had an asylum procedure in Germany, it's not going to be possible to do the same in another European/Schengen country. Having a visa however, allows you to go to Czech Republic for example. That's a different matter than asylum proceedings. But keep in mind that Germany is going to reject your asylum application if you are holding a Czech visa.