For Magical Item creation, does being a 3rd level Alchemist grant me a +3 bonus on the creation of potions? Or is it only magical construction proficency that gives me a +1 bonus to magical item creation per level taken?
Based on what I read from the book, Alchemy only helps on potion identification. :/
By the book, I'm not sure. As a Judge, I'd allow it. I don't think anybody's going to cause problems by reliably making potions.
RAW Alchemy does not provide a bonus to making magical potions.
However, the Heroic Companion adds a rule that gives you a bonus equal to your ranks, using it in a core ACKS campaign is a simple houserule.
By RAW, the answer is no. However, there is a thread somewhere where Alex does mention something about adding Alchemy ranks to potion creation.
In our game, we apply crafting proficiency ranks to rolls; +1 per rank that only applies to corresponding item (a 9th level Mage with ranks in swordmaking can apply that bonus for making magical swords). Since a 9th level Mage can make almost any magical items upon reaching a predetermined level, having proficiencies based related pursuits, e.g. having alchemy when one can make potions at 5th level, seems a waste otherwise.