Skill points are not random. You start with one skill point. You get 2 skill points for each level-up until level 5. Then you get 3 skill points per level for the next 5 level ups. The number of skill points you get per level up goes up by 1 every 5 levels. So if my math is correct (and it seldom is) level 100 would give you 22 skill points.
Stamina is the ability to sustain yourself in battle or run away. If you run out of stamina you will fight or run away much slower.