These little bear cubs are cute as a button while they are small, but they do grow fast, really fast and before you know you'll have a 150 pound grizzly bear running around your house. You should never adopt a dog based on what they look like as a puppy, because that state of being is the most temporary state within a dogs life cycle. You'll have about 6 months of puppy and a life time of dog.
During the puppy stage, it is important to train your rottie on a daily basis and consistently reinforce rules and boundaries. Your rottie pup will be very intelligent, lovable, and curious about the world around them and will want to investigate everything. Unfortunately dogs interact with the world with their mouths so it can be hard to explain to your wife why your dog 'investigated' her favorite pair of high heels like a milkbone dog biscuit.
You must establish yourself as the pack leader immediately and be prepared to defend your pack leader status. It's a lot harder to take away the pack leader status from your rottweiler once the dog has fully matured. Become the pack leader and stay the pack leader. Your rottie even as a puppy will challenge you as pack leader on a daily basis. These challenges may be subtle but they are challenges and every one that you let your rottie win will give you less authority over your rottie.
When it comes to properly raising a rottweiler, the nature of the rottie is of minor importance. The real importance in raising a rottweiler is the nature of the owner.
Nothing against non-assertive people but weak or passive people should not own a rottweilers. Period. These dogs want to dominate their domain and claim everything in it as their own, that includes you, your family, your house and all your possessions. While rotties love their families and will guard you with their life, they want to be the leader and you can not let that happen. A weak owner will do 1 of 2 things to a rottie. One, the rottie will be insecure because their owner isn't secure and that type of insecurity leads to fear and eventually will lead to fear based aggressive behavior. Or the rottie seeing that the owner is weak will naturally take charge because the owner is not assuming their rightful role as pack leader. You won't regain pack leader status with your dog without a fight.
The easiest thing you can do is be firm and consistent with your rottie. You can not let any challenge by your rottie go without redirection. Not even once. It may seem like a pain in the neck and it is, because honestly sometimes you won't want to go through the trouble of redirecting a behavior that might seem as innocent as your dog running out the door in front of you, but you must. What seems innocent to you is a major victory in your rottie's mind, and it enboldens your rottie to push the envelope a little further the next time. Before you know it, you rottie will be taking you for walks and feeding you out of a bowl. Just kidding.
Some ways your dog may challenge you: