Wise words on the newborn clothes - and a good tip when buying for friends; get the 6-12 month stuff for when everyone else has lost interest and the parents realise how much money they have already spent.
My main tip would be to get yourself a reliable babysitter early on, and use her. Even if it's just to take little Obadiah out for a walk in the pram for an hour or two while you get a nap. Being able to catch up on a little sleep, go out for dinner with friends or watch a movie is really important for your sanity. You want to do everything right and do it yourselves and that's the way it should be, but it will be extremely tiring and make you snappy and irritable with each other. That's no good for the baby either - they can already sense that you don't know what you're doing with the first one, and if you're frazzled too they will feel the stress! Relax, enjoy the learning and the wonder of it all, and don't forget the maintenance of yourselves and your relationship.
Oh, also, buy your lady a really nice tote bag. Those plasticky baby bags have nothing special about them apart from ugliness. There is no reason at all that a few nappies, a bottle, some wipes and a change of clothes can't travel around in something classy that she would normally use. I think that's also a psychological message to all involved - that the baby is part of the family and normal life, not a paramedical emergency situation.
Now, will there be a birth year Rolex stashed away?