How do I damage him? I figured I was meant to die the first time but my second go at him was no different. I am unable to get in range to hit him and after a short time he does that unblockable attack. It sucks that he sends me to a predetermined bonfire farther away then some others.

You need to destroy a crystal thing first, it's in the same room.

The second time you fight him, you aren't supposed to go back to the first place you fought him. That instance is a fight that he is invincible during.

You need to go back to the main archive halls, where the giant staircases are. There will be a passage where a bookcase was on the right side (from the initial entrance elevator) that will take you to the back half of the archive. You'll need to get up to the staircase that goes across the center of the room in the first half of the archive, pull the lever in the middle of it, then go through the passage to the back half of the archive, and the staircase will have rotated on that side. From there, you'll have to figure out where to go next.