Ask to shadow a shift, before the interview would be best, but even after is better than not at all. You want to watch the level of teamwork between the nurses, and the other staff too for that matter. Teamwork at a high level is critical for success in the ED. If it isn't there, don't do it.
The ED is no more stressful than any other unit, but the stresses are different. Learning to be comfortable, for example, with being the primary nurse for a pt coming in by ambulance with a STEMI or an active hemorrhagic stroke is stressful - and takes time! But . if the teamwork is there, it isn't a problem.
To counter this type of (transition to ED) stress, one of the best parts of the ED is that the doctor is Right There. You never have to worry about dealing with an arse who doesn't want to be bothered.
The other nice part is that you usually only have to deal with the same pt for a few hours at most. This is balanced by the, "You better treat me like I am a hotel guest," patients.
Like I said, the stresses are just different. If the ED is what you want, *and* it is an ED with good teamwork, give it a go. I know I love it!