Hi warpig.
Yes, junior warpig will need a passport. The only difference between a passport for a baby and any one else is that very small babies are not required to have their eyes open on the passport photo.
When you book your flight/holiday, make sure you book a skycot at the same time. You'll be given seats at the front (with bags of legroom) and the skycot fastens onto the wall. Your other alternatives are to have Junior on your lap the whole journey, or book an extra seat and put junior in a car seat in the plane seat.
I always found that the younger the child, the easier the journey.
When my youngest was 20 months old he was a strapping brute and I endured a 4 hour flight with him on my lap. The guy in front of me kept his seat reclined the whole time so we were squashed, and unable to have a meal or drinks. Nightmare! (He got his own back when he was kicking his legs and his (heavy) shoe flew off and landed on the man's nose!)