Acolyte

Question:

If you where to take Spellsword twice, with two different domains of power, could you then take Acolyte twice?

Answer:

Page 39: "A character that has purchased a class more than once may learn her paragon skill an additional time, but must choose a different option for the ability."

You may not take Acolyte more than once from the Spellsword class. However, if you learned Spellsword and Ranger/Cleric, you could learn Acolyte again from the second class with a different domain.

Does Acolyte come with access to higher spellslots like rank 3 and 4 spellslots?

No, but you could still use Mana mastery from Thaumaturge to activate those higher rank spells.