CarrionCrow: They'll need to be. The adventures are geared towards higher-level parties. A standard level 1 group would get killed roughly ten seconds into their first combat.
BillyMaysFan59: So would I have to export my characters after I finish the main game? (sorry for all these questions :/)
Don't be. =)
There's a person you meet who will talk about your team going across a sea of ice with them on a quest.
That's the start of Heart of Winter. You can do it in the middle of your main Icewind run, or you can export your crew to do the expansions after the main game is complete.
In a Heart of Winter town, there's a questgiver who you can follow to start Trials of the Luremaster.
When I played, I ran through the main game completely, then went on to the expansions, but from what I'm reading, the only requirement is that your party's at 9th level. For multi or dual class characters, if you have a combination of levels that adds up to 9 or more, you're allowed to.
It'll be up to you whether you want to do the expansions mid-main game or not.
My apologies, need to go for now. Massive storm, need to shut down.
I'll dig up more on that. Reading something about how if you do a certain thing in Heart of Winter before doing Trials that you get locked out of that expansion. Need to find more info.