No, “la pâtisserie” is the shop. “J’ai acheté des gâteaux pour la pâtisserie” means only one thing in french: “J’ai acheté des gâteaux pour les mettre dans la pâtisserie”.

No.

“Pâtisserie” means either “the bakery”, the practice of baking, or “the baked good”. The phrase would be translated to English as “I bought cake for the bakery” which is grammatically correct but does not have the meaning you’re looking for.

From reading your context in the comments, your setup was to choose the right word for

“J’ai acheté des gâteaux X la pâtisserie.”

where X can be one of {chez, de, pour} and have meaning

“I bought cake from the bakery”

For this situation, “de” would have been the correct answer.