To address your questions:
1) When they found out the teenagers were dead (aka the DAY AFTER the abduction), they should have announced it, and not have placed a gag order on it. If I remember correctly, in the SOS phone call, one of the teens even identified the location they were at. What this shows is that Netanyahu did not give a rat's tail whether the teenagers were alive or dead, he wanted to use the "search" for the boys in order to break up Hamas in the West Bank, which did not have anything to do with the kidnapping.
2) In retrospect, it should have been clear that Hamas did not order the kidnappings. Why? Because, contrary to typical Hamas procedure, they never claimed responsibility. It is now known that the so-called "Hamas in Hebron", a semi-independent Hamas cell, was behind it, did not receive orders from Hamas headquarters, and moreover is known more as a terror crime family than as an integrated subgroup of Hamas.
This is not the first time they've tried to play Israel and Hamas against each other. In 2003, they staged a terror attack in Jerusalem to sabotage a ceasefire. Israel being Israel, they conduct the assassination of the Hamas number 3 man, who opposed suicide bombings. It seems they have succeeded yet again.
http://blogs.forward.com/jj-goldberg/201172/unruly-hebron-clan-pushes-hamas-and-israel-to/?3) You seemed to have your facts slightly messed up. There were rockets fired, but almost none were by Hamas, rather by other local jihadi outfits. Hamas has (semi-competently) played the cop in Gaza, grudgingly dismantling rocket launch sites when they find them.
EDIT: Essentially this whole thing has been: Hamas in Hebron shooting Hamas in the chest, with Israel picking up the gun and shooting its own foot.
