1. Yes you need to join the Dawnguard to get a husky. They are protected, which means they can only be killed by the player. Watch that you don't accidentally hit them in combat!
2. Random dragons appear around every 3 in-game days. Finishing the main quest makes it more like every 6 days.
3. You can absolutely survive without touching the crafting systems. In fact, i find that using smithing and enchanting too much can make the game very easy. That said, you can change the difficulty at any time up or down to your liking.

I reccomend that you check out the wiki at uesp.net. It is by far the best fan wiki i have used and it can answer the vast majority of questions you might have about the game.