scorbunny evolves into pyrabbit then raboot it is fire / fighting
sobble evolves into sizzle then intelleon it is water / ghost
grookey evolves into chimpani then bongorilla grass/rock

eternatus is the main villain of the game. it's battle is designed to be impossible. when you lose to eternatus, marnie will give you a special pokeball designed to capture eternatus.
methinio is the name of the evil organisation lead by leon. leon is trying to prevent you and hop from becoming champion so that his daughter (marnie) can take the spotlight.

team yell is not important in the story as much as you think, the story progresses when you get the water gym badge, when you encounter bede in soulmine cave.
bede, (and many other people and pokemon) and under control by eternatus and you find this out later on in the game and your mission is to stop this.

there are the 3 *roaming* legendaries which you can only find post-game after defeating eternatus. they are designed like the moai from easter island (1 is happy, 1 is sad and 1 is angry).
zagurphia is the sad legendary it is rock/dark
zegandi is the angry legendary it is rock/psychic
zugula is the happy legendary it is rock/fairy

new galarian forms include:
zangoose becomes steel / normal and has a shield imprint on its chest
seviper becomes poison / ground and tunnels through the ground
misdreavus line becomes flying ghost and has a propeller on its head
shuckle has its attack and defense stats swapped and gets spikes on its shell and body

post game involves a lot of exploration of undiscovered areas you couldn't go through during the main part of the game.
i would estimate around 45 hours of playtime for the whole game and an extra 15 hours for post game including capturing all the legendaries.

i have written all i have seen and for the most part im quite happy by how its looking so far