If you take the bracelet off, you should be able to see between the lugs the model number and serial number at the other side, the latter should help you pin it down to a year (approximately).
If he is looking to move it on, why not contact some of the regular second hand dealers and see if anyone is interested. The hallmarks should give you the gold ct, but I am guessing 18 unless it was sold in the US in which case might be a bit less. Why not weigh the watch and compare it to the buy in gold price per gm, that would give him a starting point, but he would need to knock a bit off for the movement and crystal, which are clearly not gold.
I wouldn't service unless selling privately. Let a dealer sort it out (or not).