I've never really seen the benefits of detect illusion. The other abilities (possibily with the exception of move silently) are far more useful. Detect illusion will remove spells such as mirror image if detected succesfully. I've never bothered to max it out but I'm guessing that when it's maxed, it will act in a similar fashion to true seeing, when you will be able to dispel all illusions. I'm guessing this so if i'm wrong then feel free to correct me [img]smile.gif[/img]
The bonus merchants come from the collectors edition CD, but you can download them (for the sake of 1Kb each) from
Baldurdash
You can get some excellent items, Vailors Helm, Plate of Balduran, Shield of Balduran, Sword of Balduran, Sling of Everad, the mercy killer ring and of course the excellent robe of Venecca to name a few. I'm not going to tell you what they do however, you can find this out for yourself