How many justices decided death and innocence (and original habeas) are different in Davis?

The law geek in me is having a hard time thinking about my upcoming classes because I am so taken by the Supreme Court's fascinating little ruling this morning (discussed here), which addresses the "original" habeas petition In re Troy Davis, No. 08–1443 (S. Ct. Aug. 17, 2009) (ruling available here).  And, as explained below, I have lots and lots of follow-up questions. 

First, consider Kent's effective comments at C&C about the Davis procedural posture:

And now, for something completely different... The U.S. Supreme Court and its individual Justices have the jurisdiction to issue "original" writs of habeas corpus -- "original" in the sense that the petitioner applies directly to the Supreme Court for relief, as opposed to applying to a lower court and then appealing the denial....

The Court used this jurisdiction in the nineteenth century to review cases it had no other way to review, but the power pretty much gathered dust in the twentieth century and, until today, in the twenty-first.  Term after term, every Monday orders list has had one-liner denials of original habeas petitions.... And now comes Troy Davis.

In other words, Fed Court fanatics ought to be excited (or at least intrigued) that SCOTUS has dusted off and made use of its unique "original" powers in this case.  But, dear readers, have these powers been used for good or for mischief?

Second, consider the Court's formal two-sentence ruling in Davis:

The petition for a writ of habeas corpus is transferred to the United States District Court for the Southern District of Georgia for hearing and determination.  The District Court should receive testimony and make findings of fact as to whether evidence that could not have been obtained at the time of trial clearly establishes petitioner’s innocence.

By virtue of this ruling, Fed Court fanatics ought to be excited (or perhaps puzzled) that SCOTUS has ordered a US district court to receive testimony and find facts as to whether Troy Davis, based on "evidence that could not have been obtained at the time of trial," can now "clearly establish[ his] innocence."  But does SCOTUS have the inherent power to make district courts do its "original" work?  On the merits, does Davis has to prevail by a preponderance or by clear and convincing stanard or some other burden of proof?  And will SCOTUS immediately review the "findings of fact" it has ordered or will the Eleventh Circuit take the first "appeal" in this "original" habeas matter?

Third, consider the final paragraph of Justice Scalia's dissent from the ruling in Davis:

Today, without explanation and without any meaningful guidance, this Court sends the District Court for theSouthern District of Georgia on a fool’s errand.  That court is directed to consider evidence of actual innocence which has been reviewed and rejected at least three times, and which, even if adequate to persuade the District Court, cannot (as far as anyone knows) form the basis for any relief.  I truly do not see how the District Court can discern what is expected of it.  If this Court thinks it possible that capital convictions obtained in full compliance with law can never be final, but are always subject to being set aside by federal courts for the reason of “actual innocence,” it should set this case on our own docket so that we can (if necessary) resolve that question.  Sending it to a district court that “might” be authorized to provide relief, but then again “might” be reversed if it did so, is not a sensible way to proceed.

As a matter of pure procedure, I think Justice Scalia makes some strong points.  But only Justice Thomas joined his dissent.

Fourth, consider the final paragraph of Justice Stevens' concurrence in the ruling in Davis:

JUSTICE SCALIA would pretermit all of these unresolved legal questions on the theory that we must treat even the most robust showing of actual innocence identically on habeas review to an accusation of minor procedural error.  Without briefing or argument, he concludes that Congress chose to foreclose relief and that the Constitution permits this.  But imagine a petitioner in Davis’s situation who possesses new evidence conclusively and definitively proving, beyond any scintilla of doubt, that he is an innocent man.  The dissent’s reasoning would allow such a petitioner to be put to death nonetheless.  The Court correctly refuses to endorse such reasoning.

As a matter of pure substance, I think Justice Stevens is reasonable to assert that neither Congress nor the Constitution mean to permit the execution of a once-properly-convicted, but now-obviously-innocent defendant.  But only Justices Ginsburg and Breyer joined this concurrence (and we are told that Justice Sotomayor did not participate in the case).

In short, three Justices made clear via Justice Stevens' opinion that they view death as a punishment and innocence as a claim (and original petitions as a vehicle) to be different in a way that justified the Court's peculiar ruling in this case.  Meanwhile, two Justices made clear via Justice Scalia's opinion that they do not view death as a punishment and innocence as a claim to be different so as to justify the Court's  peculiar (and cursory) ruling in this case.

A big question then remains:  what's up with the other three Justices (aka Chief Justice Roberts and Justices Kennedy and Alito)?  Notably, this troika is made up of the three (swing?) Justices who established the middle-ground position that the Supreme Court adopted in the Baze lethal injection case. 

Based on past votes in tough capital cases, I'd guess that Justice Alito found Justice Scalia's opinion attractive, and that Justice Kennedy was drawn to Justice Stevens' opinion.  But neither put their names on an opinion.  And, because I suspect that the Chief Justice's vote may have been influenced mostly by how the Davis case would reflect on the Court as an institituion, I have a strange feeling that he may have been centrally involved in the decision to punt this matter to the district court.