Except Isreal isn't a signatory nation, and all of the land in question is part of Israel. That's not a judgement either way, there have been some attempts to change that, but the ICC doesn't actually have any jurisdiction here.
> Given Palestine is a signatory does it mean they have to take action to extradite the Hamas leadership to face trial? What consequences do they face if they fail to do that?
Almost certainly nothing. They are obligated to help, but realistically if the palestine authority had the ability to capture hamas leadership i imagine they would have done so a long time ago, as the two sides fought what was essentially a civil war a while back.
The ICC prosecutes individuals not states, so there's no contradiction here.
>Given Palestine is a signatory does it mean they have to take action to extradite the Hamas leadership to face trial?
Yes
>What consequences do they face if they fail to do that?
There's no penalties built into the statute. It tends to have diplomatic blowback. See [1] for a prior example.
Gaza isn't actually part of Israel, though, is it? Even Israel says it's not, if I understand correctly.