Bella is at least 1/2 Boxer and exhibits many of the boxer traits. They are VERY high energy and are not a dog that you can skip walks with. The can be semi difficult to train because the have sort of ADHD for dogs. When I was training Bella as a puppy (and still today) I keep the sessions very short, an always started with play and ended with play.
They love to swim but due to having deep chests sometimes they can sink a little bit, plus if you get one who is docked they won't have the ability to use their tail as a rudder so I always recommend going with a life jacket if you go swimming a lot. Bella is a true born swimmer and was supposed to be a dock dog until her health issues began popping up.
You really have to work with them on the "boxing".. they want to put their paws on everything and everyone so from day one you need to be firm on making them stay down.
Boxers are happy go lucky most of the time but they DO come from the Molloser group which includes dogs like Mastiffs, Bull dogs, APBT, Boston Terriers, Cane Corso, Saint Bernards, etc etc so socialization is EXTREMELY important or these dogs can turn into total disasters later in life and develop some serious aggression issues. Socialize, socialize, socialize. If you get a young puppy take it to friends and neighbors for meet and greets until it has all the appropriate shots to start going to classes. Start classes early and try to get your dog to meet as many other dogs as possible. The more dogs your puppy meets at a young age the better chance he'll have for being a well rounded happy dog in the future.
And I know I've told you this before but double and triple check your breeder, get tons of references and ask about the temperaments of the dogs.