Anything substantial I missed? I must say, I never encountered anything of that sort in BG1, but then again, I don't go out of my way to mess with games unless I am pushed toward it.
Arkanis is there not as much to protect the critical path (as there are two possible ways into Spellhold) , as to make sure you don't step out of bounds during the main quest. You can attack and destroy the thieves guild, but only if you do the main quest in the correct order. Which I didn't.
Regarding charm, it wasn't anything big; BG1 was more sparse on dialogues than BG2. For me it was learning that Dynaheir was sent there to learn about the prophecy and Bhaalspawn. I'd have preferred if she was the one to survive in BG2, because there seemed to be more to her character than Minsc' comic relief.
So I have to correct myself here: it was rather tidbits of memorable conversation than lore. The assassin in Nashkel was probably the most memorable one, because he is hilarious.