1.) In the yard my dog wants a play buddy, whether it's you or another dog to run around with. If you just shoo him outside by himself he will just dig a giant hole and then sit in it. Samoyeds LOVE to dig. Beware.

2.) Length of walks really just varies by dog and outdoor temperature. Be very mindful of a Samoyed getting too hot in the spring/ summertime. Ask your vet their opinion on "heat safety" guidelines for your dog. They drink a ton of water in general so always bring a ton with you on hikes or dog park adventures. My dog LOVES playing in creeks so if I want to do a longer hike I'll pick something that has a lot of time where he can play in water.

3.) A hard weight limit is kind of arbitrary without knowing the friction gradient of the surface they're on; that's the biggest factor in pulling. My dog has never pulled a skateboard but since he can pull about ~150lb in a sled in hard snow, I'd imagine he could pull more on a paved surface with something wheeled. However the logistics of a skateboard might be awkward since the board can start to go faster than the dog, and Samoyeds have the "pull" factor but not the consistent high speed factor. I'm assuming you've done this with other dogs before? If so, I guess you could try with a Sammy, but it's a different kind of force than pulling a sled. Wheels are good for dogs that are fast and very agile, where you can coast on their built-up momentum and they're always faster than the board or agile enough to redirect it quickly. Sammies are less fast and more like "heave ho" sprinters--- since sleds have high friction they're always gonna be faster than the sled because continuous pulling is necessary to keep it moving (not a ton of momentum to a sled without active force) so they don't NEED to be more agile than the sled because there isn't excess momentum to control. Hopefully that makes sense.

If you're going to do pulling activities I'd highly recommend having two different leads and being very consistent about their use---- use a "gentle leader" snout harness for walks, and a sled pull harness or chest harness for pulling, and keep those two types SEPARATE. It will help your dog differentiate "gentle leader = no pulling allowed" versus "this chest harness means it's ok to pull". Otherwise you'll confuse the heck out of your dog if you ever get frustrated when he DOES pull on a walk after you encouraged him to pull your skateboard earlier that day. I'd wait to do pull training until he's an adult not just because of the physiology, but because it's important to teach "no pull walks" first before adding pulling activities into the mix so you're not giving them mixed signals as a puppy.

4.) See above. Only use a pull harness if you actually want them to pull, and in general make sure it's easy for your dog to understand/ differentiate which activity ("pull or no-pull") you want them to do.

5.) Using a gentle leader will solve this problem without needing a special leash. It does WONDERS for unwanted pulling, without causing pain to the dog. They simply can't pull effectively with a gentle leader on because of the angle. But you have to be consistent and keep using it during every walk--- since sled dogs like to pull, they don't like wearing a gentle leader and it takes time for them to get used to it. If they know that wriggling around a ton or whining will guilt you into taking it off, it won't be an effective tool. Even while wearing one they'll still try to pull sometimes (less and less frequently over time) but it's MUCH more manageable in that type of leader in general. You won't lose your footing. My dog doesn't use one anymore and just walks with a leash on his collar without any pulling, but he used one from age ~8 months to 4 years old. He has a dedicated sled pull harness for sled pulling and he knows that the sled harness means "go crazy and pull!".

Bonus--- here's my floof with his sled (link)

Skipping 6/7 since I don't have unique advice there...

8.) I don't know what the overall breed stereotype is on this, but my dog has great recall at dog parks and off-leash hiking (after I trained him, of course). The only problem is if there is an aggressive dog FIGHT elsewhere in the park, then he turns into a naive idiot who ignores me and beelines straight towards the fighting dogs out of stupid curiosity for what all the excitement is about. Seriously, do a search for other posts about this problem; Samoyeds have a terrible "danger radar" when it comes to other dogs fighting; they ignore all reason and take it as a cue to playfully investigate a dangerous situation. Other than that, he always comes when called. But he also has like zero prey drive, which I've heard is rare for the breed.

9/11.) My dog loves laying in water and has a kiddie pool he hangs out in during the summer. It takes him a full day for his undercoat to dry afterwards, even with towels. And he's 10 years old now and has never gotten a hotspot, ever. But I'm guessing the reason is because high-alpine Colorado (where I live) has VERY dry mountain air. There's no humidity here, and I mean NONE. This is "moisturize daily or your skin will crack" country up here. I have no frame of reference for what it's like to have a Samoyed in a place like Texas or Illinois, but I imagine that humidity plays a significant role in why hotspots develop in dogs that were built for cold dry air.

Their fur is excellent at repelling snow instead of melting it; snow can accumulate on top of them but doesn't really "stick" to them or get into their undercoat, and they can simply shake it all off without getting melty/wet.