Rumors / (possible) spoilers:
Steve and Bucky are childhood friends.
Red Skull is the first super-soldier.
There will be an Asgardian guarding the Tesseract / Cosmic Cube and he will be killed by Red Skull.
Bucky joins the Howling Commandos.
Captain America's first costume is based on his Golden Age appearance and is only just for show. He gets his new combat-ready costume after saving the Howling Commandos.
Nazi Germany's advanced weapons is due to the Tesseract.
Bucky "dies" in the attempt to stop the bomber plane.
Captain America and Red Skull are fighting in the bomber when it crashes in the Arctic.
When Steve Rogers is unfrozen, Nick Fury and Tony Stark are at his side and they invite him to join the Avengers.
Red Skull survives (duh).