Backup - obvious one. Dunno how maintained it is currently, but some kind of backup plugin should be used as one crash can likely screw up your whole map.
Permissions Plugin, e.g. PermissionsEx (PEX) - The setup is quite difficult, but at least PEX is well documented. All in all, you will not be able to dodge this mess, as the OP system is way too shallow and not supported by all plugins and Bukkit only provides an API
PerformanceTweaks - Increases performance on servers by improving MC coding
Essentials - Gives you a broad set of commands akin to SinglePlayerCommands
As always: read the respective documentation before asking about any of these.
Though I dunno much about RPG plugins, one idea comes to mind:
Citizens - allows you to spawn NPCs and give them jobs like wizard (teleporter), trader, blacksmith (repairs your stuff) and so on.
Keep in mind, the Bukkit staff will not release any kind of build for the pre-release. The reason for that can be read on their page.
If you play with friends and are certain, they will not screw with you, you do not need to put much work into the permissions. However, if you are uncertain, be sure to make it properly.