What are the grounds for reversal of a finding that appellant was sane at the time of the convicted crimes?

This appeal stems from a judgment based upon guilty verdicts in three counts of attempted murder and four counts of assault with a deadly weapon, and subsequent jury finding that appellant was sane at the time the convicted crimes were committed. Appellant urges three separate grounds for reversal: (1) that appellant's confession to a fellow inmate while incarcerated at the county jail was received into evidence in violation of Massiah v. United States (1964) 377 U.S. 201, 84 S.Ct. 1199, 12 L.Ed.2d 246 because the inmate may have been a police informant; (2) that it was error for the trial court to discharge a regular juror and replace her with an alternate during the sanity phase of appellant's trial; and (3) that the trial court erred in refusing a jury instruction which outlined appellant's possible institutionalization should he be found to be not guilty by reason of insanity.