Snowy - what happens is you cope! I mean that sincerely. You are made to care for the little life inside you. You won't feel that you know what you are doing at first, but you are designed to care and provide for that little person.
To encourage you, I will tell you that I gave birth at 09.20 in the morning with DD1, and there was a delay in discharge (they were very busy) so I wasn't released until 19.30. She had slept all day after her first feed, and I thought wow, this is great. But we got her home, and she woke up at 10pm, and didn't stop wailing and crying ALL NIGHT, literally. We felt absolutely out of our depth. But within a day or two (she was like that for 12 weeks) we had got used to the fact that she was a colicky baby who had her day and night a bit mixed up. I got through it by singing to her as I comforted her, and DH slept downstairs, so that he could take over at 4am. It didn't last long, and by 12 weeks she was going to bed at 7pm, and only waking twice in the night.
Babies' tummies are the size of a walnut at birth. They need about 7mls of colostrum in the first 24 hours, and they will let you know when they are hungry. They tend to sleep for a long stretch after birth, because they still have the energy supplied through the umbilical cord until birth to keep them going at first. Then they generally wake for feeds between 2-4 hourly. If they don't wake for feeds then you can wake them and offer the breast.
Read about co-sleeping, then you can make the choice about where your baby sleeps.
Nappies - I tended to get through between 8-12 a day at first, as my babies both did a poo during every feed. Aim to have enough for 12 a day at first, and you won't go short.
You will know if something is wrong - Not waking for feeds, very pale skin, limp, or a high pitched cry are a few of the signs. It is never a problem to call for assistance if you are worried.