I'm feeling particularly chatty after today's shift (don't know how, I worked my butt off today and am about 10 minutes away from passing out... maybe I'm giddy?). So I figured I'd post another one for you...
If you want to be in an ICU, the managers will want to be sure you can handle the stress. They might ask you if you've ever been present during a code, and if you've ever worked around end-of-life care for patients (being able to accept death and the environment that surrounds it often separates the ICU nurses from other nurses). They're looking for maturity, an ability to do your job without becoming overwhelmed by the fast-paced and stressful environment, and this is for good reason: they want you to STAY working there, and they want you to handle stressful situations well (for example, completely falling apart and losing your ability to be a nurse during a difficult assignment is a problem when the patient needs care). They might also want to ask you a simple question: Why do you want to work in the ICU? Be honest, but put some thought into your answer beforehand so you can express yourself well.
As for critical thinking... try to find a time when you put two and two together about a patient and didn't need someone to spell it out for you... a time when you knew, based on a patient's condition (vital signs, assessment findings, etc.), that something specific needed to be done. For example, it could be as easy as knowing to notify the doctor (if an oncology patient develops a fever, or a patient's neuro status changed suddenly and pupils are unequal, etc. etc.). They might ask, they might not. Depends on the manager.
Anyway, I hope that helps a little. Good luck!