My opinion on your queries are as under:
1) Can the prosecution read the punchnama from the 1st case into the 2nd case.
Opinion: No, it can not be read.
2) Can the Hob’ble Judge allow the same?
Opinion: No, the Court should not be allow the same.
3) Any citation where it can be said that copy of punchnama from 1st case cannot be used in the 2nd case.
Opinion: For citations you have to search your self or contact a lawyer with all the documents, the Citation may be vary and depend on case to case.
4) Can the Punch of the 1st case be examined in the 2nd case by the prosecution. Punch has not taken any part in the investigation of the 2nd case by the IO.
Opinion: No, they can not be examined in 2nd case by the prosecution. if they examined then it will be examined as formal witnesses.
5) Can the prosecution use the CA report from the 1st case into the 2nd case.
Opinion: Yes, prosecution may use the CA report of the same in 2nd case but can not be used as preliminary evidence, it may be secondary evidence.