I'm going to guess your biggest problem is he is at the dreaded 9 months old. I swear, that's the one age more people have come on here with troubles at. However, maturity won't overcome these problems without intervention. He needs a teenage exorcism, sort of.
You cannot skip exercise just because of snow and cold (or rain and heat. Well maybe heat.) and especially you can't at his age. Once he's past, oh maybe three years old, he might be able to miss a day, provided that all other days he's getting enough. When he does get exercise what do you do and for how long? At that age mine was getting 45 minutes to an hour off leash twice a day and he was in training classes with daily homework. Mind work helps. In the episode you describe above I might have tried a training session to give his evil (kidding) little mind something to do. As Tanya says, that would be an appropriate activity. Are you taking him to classes?
what does this mean? Later you say you did correct him. What is the correction, why could not do it the first time you mention it.?
Yes, I think it's good you bring a behaviourist or a least a trainer in to observe. It's really hard to take a step back and look at what you are doing, someone else can do it better. Good luck, I doubt this is aggression but you do need to learn how to work with him and what actions you should take. Your Dad should be there too.
Oh, and yup, crazy zoomies just After a walk is the norm at this house. I encourage them, outside and no biting me and I stand in a safe corner of the deck so I won't get knocked down.