Good luck to you and you're little guy tomorrow! I'm sure everything will go smoothly. Surgery really is the best thing for these types of injury, but it is expensive and yes a lesson to be learned to be extra extra careful with the little ones, even though accidents can happen so easily.
He'll probably won't be himself for a day or two but after that they typically are fine! Sometimes the 3rd day after surgery is tough on them too. That's when the anesthesia is wearing off. The hardest part is keeping them confined after the surgery I find, especially if they are a puppy. You'll notice how much less pain they are in after a few days and it will make you feel so much better. It gets easier as the time passes too. Also, I got the stairs for my puppy too, but they are the six step ones. I thought it was the right size for my bed (even though I probably won't let her up on it), but they are way too high and they scare the crap out of me. I think they look way too dangerous for my little one and the step width is so small. I might have to find a different type of just get some really big pillows to put down around the sofa/chairs if she decides to jump up on them. Anyways, hope all goes well and keep us updated on how your little guy is doing.