I bring my own stethoscope in. We also have infant scopes on the unit. When we float to NICU each baby has their own stethoscope. Wait and see what the unit does and do likewise.
Rather than cramming before you start, come in attentive and ready to learn and bring a good attitude and work ethic with you. After a year on med/surg you should already have good assessment skills. You'll need to adapt them a little, but that's something that will come with actual patient care.
Be teachable. Pay attention to your preceptor(s). Look at how individual instructions and events fit into the big picture. Many newbies get so caught up in trying to impress others that they miss things. Not saying you are doing this; only that it's a common pitfall.
If you want focus on one area that is substantially different from med/surg, concentrate on learning how to help breastfeeding moms. This is a biggie on postpartum. Ask if you can spend a small part of your orientation shadowing the lactation folks. You'll be able to get the straight scoop not only on breastfeeding knowledge itself, but on how to communicate it to others.
Finally, be where you are. If you don't know something, don't try to fake it. Determine who the safe people are and ask your questions. Give yourself time to feel comfortable. Don't worry that you'll make mistakes. Of course you will. Just learn from them and move on.
If you can balance your excitement with a level head and resist the urge to try too hard, you'll most likely find that postpartum is a great place to work, one that can influence many families and give babies a great start.
I wish you the best.