For dating the watch, as mentioned the movement was made between 1959 an 1961, the case 1961 as the case number indicates. For the broad arrow or the "duck foot", the history is explained here:
http://www.omegawatches.com/planet-omega/bond/on-her-majesty-s-service
"the famous Ministry of Defence ‘Broad Arrow’ symbol which illustrated that the watch was military issue. This ‘pheon’ is usually found on both the caseback and the dial. Confusingly, the term ‘Broad Arrow’ is sometimes used for a watch with a particular style of hands, but here it refers to the British symbol that is found on many army-issue items, including guns and knives."Click to expand...