1) Different species of coniferous tree vary in shape.
2) 'Rudolph' teaches that being different can be a good thing. Though at first laughed at for being different, Rudolph eventually proves himself the most useful of the group.
3) Songs do not have to be sung to their traditional tune, so there's nothing to stop anyone singing 'Shepherds' to a more lively tune (I can imagine a gospel choir singing it). However, the traditional tune is slow because it's meant to be sentimental and romantic.
Happy Christmas, chakka. :-)