Congratulations on your future as a nurse! Stressful situations occur in NICU, postpartum and just about any area of nursing. Birth, death, illness mental and physical, life changes marriage, divorce, nursing school all stressful in their own ways. It depends on your investment and ability to care for yourself, take time off and other outside interests.
Violence occurs in most areas of nursing. ER violence is well documented. Any psych work can be violent, it is one of those learning times on developing the "eyes in the back of your head" or the ability to "sense" the atmosphere of the unit. You are taught de-escalation techniques and CPI. This ability to sense the vibration of the unit is something that I developed over years of working in psych. I was able to listen to the unit and know when there was something that was going to happen. Something I don't know how to teach or explain to you.
As for children versus adult, I've worked both and prefer kids and adolescents but after 20 years I was burned out. I became too enmeshed. That being said I enjoyed working with the kids. I remember after a snowfall, grabbing trash bags and going out with the kids for sledding. Also worked with a company that had a Prom for the teens. I now am working in addictions(which is classified a part of psych).
Any type of nursing can be rewarding and enjoyable. You just have to have an open mind and be able to "look out of the box". One of the many benefits of nursing is that there are so many different areas in nursing. I have also worked in ICU, blood drives, home care, forensics. Enjoy and have fun whatever it is you do.