Tsel,
The narrative of the additional cut scene at the beginning should be displayed after the whole sequence ends. I don't remember how, but I guess Xardas simply says it to you via subtitles.
I totally agree that the addon adds lots to the game. Apart from the obvious additions, it also alters the feeling and atmosphere of the game to be closer to G1. Oh and if you missed ladders in G2 then you will be delighted to hear that there are some in the addon world. Two to be precise. Isn't life great?
The addon is a little harder than G2 classic. This was probably mentioned already. If you can't cope at all, then try the
difficulty changer (thread) that aldee_ made especially for this eventuality.