My baby is 6 months
Yes, you can. For our son, it was incredibly helpful for him to have his pacifier. Some kids are great with just their fingers. But if yours is a pacifier kid, empower them to use it.
definitely! give them what you can to help them self-soothe. even adding a little lovey/comforter is good if you're comfortable with it
I would think you can and should use it depending how old baby is but I'm not read up on the particulars so maybe not helpful sorry!