Question about learning sorcery


In the "magic item" section, in the text about grimoires, it say that a spellbook gives +4 to the Knowledge check for studying, and that a spell book contain a certain amount of spells...

I conclude from this, that a sorceror can study and learn spells whenever he wants, that he is not bound to raise a level for gaining spells.

Is this correct?

And if its correct... how long time does it take to learn a spell from a spellbook, and what is the DC for the knowledge check?

Thankful for help on this one.
No, it is referring to the Knolwedge [arcana] checks that a Scholar with the Independent background needs to make when he gains new class features. See the Scholar backgrounds for more details.

Hope that helps.