The Drunken Lizard Pub

some keywords couldnt find an answer with search: skill books level alchemy training trainer

Are there multiple books for a skill and will they only give you skill points if you are already at a certain skill level for the concerned matter?

Not from game but an example to make myself clear: game X has 2 books on swords:
1. Master in Sword will give you 2 levels in sword when you are at 10 in sword and will not give you anything if you are below 10.
2. Noob in Sword will give you 2 levels in sword only if you are level 1 or 2 in sword...

In Eschalon Book I, there is one training book for many of the skills (though not all). The book for a particular skill (Say, "The Art of Brewing" for Alchemy) will either give you the skill if you have not yet learned it, or it will give you two levels in the skill if you already know it. Very simple.

Book II may have more expanded training books, but we don't know yet.