[DinkumThinkum]

Everything you need for the Staff is in the Rift; you don't need to be in the castle yet. I'd suggest going back to the Rift and finishing up there before heading to the castle. (You'll probably want to go back to the Rift to take care of something later on, but other than that you can finish almost all of it before going on to the castle.)

Hint: for one key you need, inspect the various wands found while fighting the Priestesses in the Rift.

In the castle: if you join the Templars, all the Rapax will become friendly and stop attacking you. Unless you already have a portal set on Ascension Peak (past the landslide), you have to join the Templars to access the teleporter that will get you there.

You can find the Templars up on the balcony in the big room on the main floor of the castle; talk to each of them until you find the one that starts the process of joining the Templars, then follow his instructions.