My personal experience with Siberians is that you could walk them 10 hours a day and it's not enough, because they need to run. I do urban mushing (dogs hooked up to my bike). We go to and from the dog park, 1.5 miles each way, about 3-4 times a week. We spend at least an hour at the park for them to run and play. I also do separate runs with just Kaytu because she is so much faster and has more energy, so that allows her to run as fast as she wants; we go about 5-6 miles and do that once or twice a week. With Denali I do agility, which is class once a week and trials about once a month. I don't do walks much at all honestly because it doesn't seem worth it. I do them just to work on leash manners.
Mine do have a very good "off" switch. We take days off where we don't do anything at all and they are ok with that. If they start having zoomies I let them in the backyard and run around with them for 5 minutes until they are done lol. One day off at a time is about all they can handle. On the second day they'll be wrestling each other more and in general more restless. On days we go to the park or such they are content to be calm and quiet the rest of the day. You can train a good "off" switch by getting the dog partially wound up with a toy or something, then putting the toy away and waiting for the dog to calm down. Reward when the dog is calm by playing again.
If they don't get enough physical and mental exercise they will get bored VERY easily and make their own fun by ruining your everything.
Denali I've had since a puppy and she grew up with my 2 cats so is absolutely fine with them. I made sure to socialize her (and still do) with many small dogs. She knows the difference between a yorkie and a rabbit very well. Kaytu we adopted when she was a year and a half old, and she has been totally fine with the cats. That said, I never leave any of them unsupervised together. The dogs are **ALWAYS** in a crate when I can't be watching. It keeps them safe, keeps the house safe, and keeps the cats safe.
As they've been bred to run, often the first thing anyone will tell you is to never let them offleash. I agree to some extent. Because we got Denali as a puppy I was able to have her offleash all the time to take advantage of her natural instinct of following me. We've worked hard on recall and I can have her offleash in unenclosed areas no problem. Kaytu, I don't think she'll ever be ok to let offleash because we wouldn't see her again until we got a call saying she got run over. Never risk it. Don't take any chances. Unless you know, 100%, that your dog will come to you, then don't let it offleash in an area that is not fenced- any breed, not just huskies.
On that same note, do not *ever* leave a husky in the backyard unattended. Unless you don't mind a yard full of holes or the dog escaping. Kaytu can climb chainlink fences and I have no question about her ability to jump a solid 6 foot fence. She's jumped through window screens to get out before.
Digging is a natural siberian behavior. I prevent it by not allowing unsupervised access to the yard, and by giving designated areas to dig- in dirt at the park, or sand at the beach/volleyball courts.
I'm sure you know about the fur. They shed quite a bit, and fully blow their coat twice a year. NEVER shave them, except as required for medical reasons. Do not shave them because it's hot outside, that is not a medical reason, and they're actually more at risk of heat stroke when shaved. Their bodies are meant to regulate their body temp with all that fur. Keep them cool when it's hot outside by keeping them inside, or providing a kiddie pool with a couple inches of water in it.
Separation anxiety is also a common husky thing. It can be tough to tell if the dog is actually having separation anxiety or if it's just boredom. When I'd leave Denali with my parents to watch her, she would get a sock or shirt of mine and curl up with it. That was separation anxiety, grabbing something that had my scent. When I left and she ripped up the cat bed, that was boredom.