The only things I used out of my bag were:
my own pillow
camera
clothes to go home in
clothes for Alyvia to go home in
car seat (obviously)
toothbrush/paste
hairbrush
chapstick
Just about everything else I brought I didn't use. I brought comfy jammies to wear in bed after she was born, but I was bleeding so much that I didn't want to ruin them. Same with my underwear. I used those little net panty things they gave me. I didn't read the book I'd brought, didn't listen to my mp3 player at all, didn't dress Alyvia up in the clothes I'd brought for her (I was scared I'd break her if I tried to put them on her).
They provided all of the diapers, all of my pads (yes they were huge, but I was bleeding THAT MUCH, so I didn't mind it at all), a manual breast pump, nipple cream, two diaper bags, a crapload of baby shampoo...
Yes, they have showers. In fact, you'll probably have a nurse help you shower. You'll probably still have an IV in your arm (which means an IV stand just outside ths shower) and you'll be bleeding like you've been shot or something. And they'll probably have you pee in this plastic bucket thing that kind of sits inside the toilet to check for clots (I think that's what they do that for, anyway).