Vetern EQ1 players won't have any huge advantages in EQ2 over people who have never played EQ1. The biggest advantage you'll have in playing EQ1 is having a better learning curve with the interface.
It should be noted here that most EQ1 players should take the time to remap the keyboard settings when they first start playing, it'll save you alot of grief. For example, in EQ1 the D key had you duck/crouch while in EQ2, the C key is the default for that. And in EQ1, the Backspace key brought up the map while in EQ2, the Backspace key will have you replying to tells. If you go into the options and take the time to remap the keys to what you're used to in EQ1, you'll help your learning curve considerably.
Aside from that, there's no overwheming advantages EQ1 veterns will have in EQ2 over true newbs to Norrath. Knowing the History, Lore, and Locations of Norrath will help a little and you'll understand alot of the side jokes (like the Gnome named Gornit in Brumbleshire), but it won't do much else otherwise. The world has literally been ripped apart by The Rendering (a series of massive earthquakes that fragmented Antonica into several smaller continents) and The Shattering (the recent explosion of Luclin that sent pieces of it crashing towards Norrath, doing even more damage to the world). Don't expect to find places where they once were in EQ1.