1) This is a known glitch. Check the stickied thread at the top of this forum for more on it.
2) Pull up the castle and click the red Revenge! button. You have to do it when someone has recently attacked you.
3) The task requires both characters. Make sure that BOTH Homer and Barbarian are free. If only one is free, the task won't be available.
4) You have to progress further in the quest lines to completely unlock these items. It's a stupid feature of how they set up the event, but it's not a bug.