Most watches can be assembled in just an hour, give of take a little. Of course when you move into more complicated watches, the time for assembly can turn into a few hours. On the other hand, it likely took many months or more for the watch and all of its components to be made and finished to such
The water resistance will not suffer due to using the original acrylate plastic crystals. Plus, the Rolex plastic crystals are super cheap, while the Rolex sapphire crystals are much more expensive. I think one of the coolest parts of the older models is the thick, domed plastic crystal.
I am a certified swiss trained watchmaker and I work on lots of vintage Rolex. Your watch will need a professional cleaning and oiling. From your description it sounds as though the watch is running, which is a very good sign. However, I recommend that you do not allow the watch to run until you hav