Is there a pattern to how skills are acquired?

I can confidently state that characters don't level up beyond level 25 when playing in the Ubisoft version. If you have plenty of time and play on one computer, it might happen, but that's rare. As for skills not appearing, that happens often. The skills you gain depend on where you're leveling up. If you level up in the Sanctuary, the game will offer skills that are relevant, but it won't offer skills that are completely unrelated. Besides, there are approximately 82 skills for each race, and there are only 40 levels (has anyone actually leveled up to 40 in multiplayer?). So, it's inevitable that some skills won't be offered.