"Somewhere there" is fine. And the English "somewhere OVER there" is certainly used. Problem is, that may be a different sentence in Czech. Perhaps one of the CZ natives on the team will weigh in on that.
I am not sure. For me, the Czech word order is quite specific. The sense is you are discusing some place in connection with some person and then you say he actually lives somewhere there. So I would not use "over there" here.