Thanks for the tips, Sigs and Stabbey. When I first played this (back when it was only ED), I never thought I would beat it. When I got all the way to the Zeppelin escort and kept getting it destroyed, I almost lost hope. Then, I saw this thread and the tips worked perfectly.
Also, it helped that I completely forgot about the eye of the Patriarch. For some reason, I thought the eye was what the Zeppelin was shooting with. Oops.
Anyway, thanks to this thread, I got past the Zeppelin escort, then kicked the (bleep) outta Ygerna and Bihrlihn (with some help from my creature).