1. You know all zanpakutos are part of their users but still all of them need to fight with them in order to achive bankai.
2. Yes he used blut vene, he can give him some power (but not full), just like Kurama can do.
3. Not really sure what you want to say with your question? I think Quincy or Ryuuken can train him, or maybe even Old Man Zangetsu. If you are thinking when is Ichigo going to train, after he lose this battle in RR.
4. He didn't learn it from Zangetsu, he learned it from Old Man Zangetsu/Yhwach. Which is confusing and still unclear how he done that.
2. Yes he used blut vene, he can give him some power (but not full), just like Kurama can do.
3. Not really sure what you want to say with your question? I think Quincy or Ryuuken can train him, or maybe even Old Man Zangetsu. If you are thinking when is Ichigo going to train, after he lose this battle in RR.
4. He didn't learn it from Zangetsu, he learned it from Old Man Zangetsu/Yhwach. Which is confusing and still unclear how he done that.