It’s definitely possible to survive without these, but survival is easier with them. I recommend playing the game for a few dozen hours, then go to Whiterun and use all of your stores-up materials to binge on smithing. Alchemy and Enchanting didn’t matter as much to me as Smithing did.
No clue, sorry.
It looks like dragons tend to spawn more often after fast traveling. For vampires, it looks like frequency of attacks escalates as time goes on: https://steamcommunity.com/app/489830/discussions/0/1648791520840376016/
It’s definitely possible to survive without these, but survival is easier with them. I recommend playing the game for a few dozen hours, then go to Whiterun and use all of your stores-up materials to binge on smithing. Alchemy and Enchanting didn’t matter as much to me as Smithing did.
Enjoy having fun with a great game!