2004 Chevy Silverado engine seized

My 2004 truck engine seized. I'm told it's because the oil pump failed. I have 3 questions:
1. Would the driver hear anything or be warned of this problem prior to the engine seizing?
2. Is this pump computer controlled and how does one check it in the course of regular maintenanace?
3. Approximately what would it cost to replace this engine in new york metro area?

thanks