Few questions about FAB


Few questions about FAB

I have a button with more icon, can I bind FAB to this button ? I mean instead of first circle button, can i use another button ?

I have a file input as below, how can I trigger with a FAB opened button ?

input#_file.button.button-big.button-fill(type="file" accept="image/*;capture=camera")

I can get file input open when I just put in html, but I want to open it with first a tag below

              i.icon.material-icons.md-only File
              i.icon.material-icons.md-only Image

and my final question, I use FAB inside message bar component but its not seem properly, how can I fix it ?