My baby is still just walking in the house, but she is not tripping over the sandals.  When sitting in her car seat, she does her best to kick them off - she is sometimes successful at getting one shoe off (using one shoe to push off at the strap). But if she is playing around the house, she leaves them on.

I'm not sure where baby shoe sizes come from, but at 12 months my daughter is still in size 2 shoes with plenty of room to grow.  If you don't know your baby's shoe size, I recommend measuring (and using the size chart) rather than following age guidelines.  The size chart can be found on the manufacturer's web page.

I purchased the shoes in fuschia and the bright pink is adorable.