I do not think you have a problem going into other countries. But speak to an immigration attorney on that. You can call the court and find out the bail, post it and get the warrant off. Retain an attorney and deal with the case where ever you are. It is not a felony warrant.
The failure to show up in court is probably the least of your problems; as a colleague noted, you can contact the court, find out your bail, and post it (or have a bail bondsman post if if you can't afford the full bail. (I'd be happy to recommend a very reputable bond company if you're interested.)
As far as the leaving the scene, uninsured motorist, and expired registration tickets go, that's a whole other story. You are looking at some very serious penalties in the form of fines and court fees, as well as a potential/probably license suspension.
The Simon Law Group can help you; our attorneys have years of experience assisting NJ residents with motor vehicle violations across Central and Northern NJ. Call the office to set up an appointment at 800 - 709-1131.
The foregoing is not legal advice, and nothing in the foregoing shall be deemed to create an attorney client relationship. If you feel you need to speak with an attorney regarding your issue, it is recommended that you contact an attorney with expertise in your area of inquiry. The information related above is purely for informational purposes, and should not be acted upon without speaking with qualified counsel familiar with you specific situation and the laws related thereto.