try searching for a hebrew keyboard for android apk, you may be able to install it and use instead of the default virtual keyboard.
In order to see Hebrew on LCD you would need to install special fonts, which I think exist for android, but I don't know if they'd work on the eDGe.
As for seeing Hebrew on the e-ink screen, I think that's a matter of having a properly encoded PDF (with embedded fonts) but I could be wrong.