1) I don't think a blade can just keep extending with energy, it has to have an end. Just like Renji's it can extend a fair bit, but it has to come back, so change that bit

2) Physics don't work that way you know. The faster something goes, the more chance it has to rip through you. So might want to alter that.

3) Fine, cool down 4 post

4) Fine, it can last between 3 to four post, cool down 6