Without the serial number we cannot tell you what year the gun shipped, only a range of several years for the 10-5. Photos showing condition would be helpful. Value would generally run from less than $450 to $800 depending on condition and other factors
What does the NPD 18 stand for? If it is a police department marking there are many, probably hundreds, of cities, townships, counties and states that could be represented by just the letter "N".
All s&W swing-out cylinder guns are hand ejectors. The serial number is on the butt of the gun and will contain a letter and up to six numerals. The 5 digit number you show is probably the "assembly number" that means nothing once the gun is completed.