Chamber of Secrets set 4730 assembly issues
I don't own the set but found some pictures of the assembled Set 1 and Set 2

It looks to me that you can reenact the scenes of the movie with this set, therefor you have the different sections of the room, where in the movie the action takes place. You can combine the different sections to create 1 corridor by placing them as shown on page 61, the bricks of question 1 &amp; 4 can be used to connect them.

The towers are placed on the wall sections for example as: http://www.brickshelf.com/cgi-bin/gallery.cgi?i=5727533

Pages 62 and further are indeed alternative builds, I don't know if this can be done with the parts of this set, but I thibk so.