How do I set my Samsung Intesity (u450) to 24 hours clock? also is there a way to have all numbers locked even 911?

You can change your Intensity to display a 24-hour clock by pressing the Menu button and going to Settings & Tools, then Display Settings, then Clock Format. Use the side arrows to scroll through the different clock choices -- some of them are 12-hour and some are 24-hour. Then just save your changes when you find the clock format you like.

I don't think you can prevent your phone from calling 911. It's built in as an emergency function. Short of turning your phone off or putting it in a holster or case that doesn't allow access to the number pad, there is no way to disable it from calling 911.