All dogs are good with children if they are properly cared for and trained - and by trained I mean the children as welll as the dog!
Hair - not as bad as some dogs I could mention
Excitable - IMHO yes, rather on the boisterous and bouncy side in the main. Not, TBH, the first dog I would be advising people with young DC to have unless they were like me and tended to tell their DC to get out of the dog's way and get up and stop moaning if he knocks them over! I have never owned one but have known quite a few people who have. They tend to be one of those mad breeds which takes some years to calm down. This is however only my opinion, from family having them and a couple I have met in rescue/owned by fellow rescuers. Rescue's opinion is that overall the breed is too often taken on by young families which don't realise the amount of bounce in a Dally or the level of training and commitment needed - I've had several conversations with very cross Dalmatian rescuers who are frequently approached by Dally owning parents of young DC who don't want the dog because it "keeps knocking little Johnny over" or they "can't cope with a toddler/new baby/pregnancy and the demands pf a Dalmatian"..
Re cats, the same as the answer to what they are like with children. An older dog might have issues - most can be overcome although I have had one failure in that department with a foster dog (not a Dally).
Have you considered having a word with Dalmatian Welfare?
Apart from my belief that because dogs are being killed in their thousands each year in pounds owing to lack of homes a puppy or dog bought from a breeder when he could have been adopted from a rescue deprives a pound dog of his life, even if you are set on a puppy these people know their breed and will be able to advise you very well. Better to know now than regret later! You could even consider fostering, to get a taste of life with a Dally.
If you are willing to consider a rescue dog, ensure the rescue assess, homechecks, neuters, vaccinates, microchips and will guarantee to take the dog back at any stage in his life should your circumstances change and you are unable to keep him. And, should you decide that a Dalmatian is not for you after all, please don't write off all the other lovely large breeds waiting patiently in rescue for a home.
HTH