Hm, I was wondering myself why Jango didn't fly to safety when he realized that Mace would get him. Didn't notice that the rocket pack was ruined. Thanks for clearing that up.
As for the head... I just assumed it was still inside the helmet when Boba picked it up. Poor kid. Good thing it didn't fall out. I guess whatever kept the helmet on while the guy was alive wasn't cut off by Mace's super-clean slice.
Finally, I must say I wasn't prepared when Jango died. So suddenly and violently. I think I may have thought "No!" to myself just then. He was such a cool character. That armor is just awesome.