Is the murtad woman upon returning to the fold of Isalm responsible for Qadha Salaat which she had missed when she was a murtad for 5 years?

Answer

No, she is not liable for the Salaat she did not perform during her evil murtad period of 5 years.

raka‟ts Sunnat of Zuhr, the Fardh Jamaat begins. What should one do?

A. If you are in the first or second raka‟t, then complete two raka‟ts and join the Jamaat. If you are in the third raka‟t, then complete the fourth raka‟t as well. If these Sunnats were terminated after two raka‟ts, then repeat the four Sunnat Muakkadah after the two Sunnat Muakkadah which follow the Fardh.