Problems since the update

Hello, I have been having problems with Minecraft ever since its update. 

1. I cannot download any of the new worlds that you have put in the game.
2. I have been unable to join any server or friend in Minecraft.
3. It keeps lagging and logging me out of my account when I know my internet isn't crashing.
4. I have lost all of my worlds and keep losing my worlds when i try and get them back up again.     

Please fix this.
Sincerely, Mikora.