No, longer spurs means the spur is closer to the horse. you just need to have a good control of your legs. A spur is hard if the surface hitting the horse is small, sharp and fix. If you are looking for softer spurs, look for spurs with large diameter rowels with a lot of points which are not sharp.
Not necessarily. It really depends on the shape of the spur and then how the rider uses it! One of my soft spurs is a long rounded spur. And one of my harsher ones is short with a flat tip.