Annie,
The bright finish is mainly some sort of oil, mostly linseed oil or Deks Olje, these days. Inside they are often painted to protect them from the sun (The south-east coast of Norway sits in the lee from all the lows from west, so the summers are generally quite sunny). A boat with bright finish is easier to sell here as they show better the conditions of the wood.
Actually, several of these motor-snekker have a mast hole fitted far forward, probably meant for a sprit-sail with a little jib. Many of these boats have a wind screen running 2/3 aft on the sides. The brilliant thing with a junk rig is that it will work perfectly well with this layout. The windscreen even adds freeboard and safety.
And yes, small dinghies can have junk rigs. I bet my 5.5m/200kg Oslo-dinghy with JR, Broremann, was by far the most well-sailing of them all, and the safest as well. Just search for Broremann on Youtube.
Arne