Just a few changes. Your dialogue is pretty good
-Hello! Can I speak to Ms X, please?
-Hello, how are you doing? I'm the student from Russia who's coming next Sunday.
-I'd like to know if there's anyting important I should take along? (...)
-All right, and what about a power adaptor? Do you happen to have one or should I bring one with me?
-I would really like to bring along something from Russia for you. Could you give me an idea what would interest you -maybe a book or a souvenir?
-Thank you very much indeed! That's all I wanted to ask you while I'm still in Russia. Looking forward to meeting you. Bye-bye!