Casual view here (again). Can you help me answer some questions?
* Stannis: How anticlimiatic was his death? He seemed calculating and at least somewhat smart. I was bit disappointed to see him die in such a stupid way. Why did he overextend, only to get slaughtered? He existed for many seasons and his death seemed out of character.
They better not bring back Jon Snow. That would be utterly stupid and cartoonish. GoT's strength was that it always focused on politics and human drama, and only utilized fantasy element to compliment the story.
Stannis felt that he no longer had a choice. He had already spent so much and gotten so far. He was probably still hopeful that the visions from Melissandra were true as well.
He was genuinely surprised though at the end from a strategic standpoint - he always thought that the Boltons were going to hole up in their castle and withstand a siege. Why wouldn't they? It's what any wise commander would do.
In a previous episode Roose Bolton admonished Ramsey for wanting to take the initiative, saying that a wise commander does not go out to meet an enemy head-on in the open when he has the safety of walls, months' worth of food stores, and a bitter winter outside that can wear down the enemy for them.
Stannis knew that any ordinary commander would play it like this, so based on this sound logic of traditional military tactics, Stannis continued to march forward after the mass desertion, and even gave the command to start setting up infrastructure for the oncoming siege when they came into sight of the castle. That's when they were rushed by the entire force of Bolton on cavalry, which surprised everybody.