Cows milk in cup or bottle!

My son was 12 months on the 16th March and we switched him straight over to cows milk. He’s been absolutely fine with it apart from he won’t drink it cold so we heat it up a bit for him.

I’ve read lately that they shouldn’t have a bottle after 12 months because it can cause tooth decay? Is this true? And what cup would anyone recommend for baby to have milk from?