Is it permissable to catch up on Karbanos or other tefillos while the chazan is saying the repetition or kaddish or during the torah reading. I daven in a shul that moves very quickly and use the times above to say Karbonos that I miss. Is that OK?

One should neither talk nor even study or make up parts of the prayers during the repetition by the Shatz (Shulchan Aruch Orach Chayim 124:7) or during the reading of the Torah (SA OC 146:2). Although making up Korbanot or Pesukei Dezimra can be done all day. Rabbi Ro'i Margalit