Shalom
0) Apart from the greeting we are forced to speak English here, if you want to communicate in Hebrew feel free to send me a mail.
1) I don't know too much about any users mailing list (I assume they are out there

). So far this forum has been more than enough to me.
2) Try FreeRock GNOME. There are many other GNOME projects for Slackware out there (gware, linuce, dropline). Never tried them, maybe they're good. I know FreeRock and it's good for me. Pick the one that suits your needs: I understand all of them are very complete.
3) I keep a Hebrew-all KDE in my mother's laptop (currently using a forked-by-me Slackware 10.2). Not too many complaints so far (apart from some apps and games -as usual, and some translations are not complete). Not tried with the bare console: so far I have had no need of it. I usually compile my kernels with support for "Hebrew characters support" in NLS under "filesystems". My ID3 tags, however, are all messed, and I have experienced problems when connecting via Samba to Hebrew-speaking W1nd0ws networks. And I have to be changing the character encoding every now and then. But I'm -mostly- satisfied. (maybe because I don't mind having some things in English).
I do think the successes/fails here would be pretty much the same as in other distros because most of the time userland apps are run from inside X and most people I know use the console in English.
4) I think my tags problem is related to those %^%&^% encodings.
5) Spend 2 hours. Learning basic, useful bash is that cheap. I almost NEVER use vi, however I do edit most files "by hand" using mc and kwrite. If you have edited files by hand, you will see that Slack configuration files are not that difficult to manage.
Behatzlacha! (good luck for those who don't understand

)