Again, this link will walk you through updating the firmware: http://wiki.maemo.org/Updating_the_tablet_firmware

This link will walk you through installing tear: http://talk.maemo.org/showthread.php?t=28539

Go here to browse through more apps online: http://maemo.org/downloads/OS2008/

You can also browse for apps using the tablet's on-board Application Manager.

As for disabling java and plugins, once you install tear and have it open, tap the upside-down V on the bottom right, scroll to the bottom of the list that pops up, and unselect java and plugins.