Ok, well there was a thread started by someone recently about what to pack for a CS, so you could start there for your hospital stay. If I can find it, I'll post the link. I hope some others pop in to help out as my memory is so bad, feels like years ago I was in the newborn stage!
It depends what brand of nappy you use how often you will need to change but I think if you aim for around 10 changes a day, you should be ok and corner shops nearly always have nappies anyway.
I didn't need breast pads at all so I'm not sure on that one. You can get cloth ones though, so then you could re-use and not run out.
Other stuff (essential or not):
A few linen changes for wherever baby is sleeping
Mattress protector if you will co-sleep (even if you think you won't, you probably will at some stage)
Some bath wash/moisturiser etc (IMO natural is better - Moo Goo is best! LOL)
A grobag (my DD hated them but many love them)
A couple of small bottles/pump/milk storage bags if you want to express
Comfy clothes for bub - don't go overboard with cute 'special' clothes because they probably won't get worn.
A play gym with a padded mat underneath
Books -start early! LOL I am biased in that area.
Baby panadol - you'll eventually want it when you can least get out to get it.
Wipes - I'm guessing here, a pack a week? Maybe two? Someone else with a NB might know better.
A sling or carrier of some sort
Muslin wraps are great for so many things - bigger ones are better. I had about 10 and used them all.
Night lights for getting about without waking bub
A really small torch - fantastic for checking on sleeping bubs
Movement monitor - I LOVE mine - peace of mind is priceless. Many don't use one at all.
Nice soft towels for bath time

Oops I have to go. Hopefully other ladies will add their own thoughts and wisdom. If I remember more I'll pop back later.