i had an external harddrive.  i use it to store things.  i guess with my mac it automatically starts backing up my computer.

1.  i backed up my computer before the internal harddrive crashed a couple months ago, but when i got a new harddrive put in, i plugged in my external harddrive to copy my files over and it started backing up my new empty harddrive and i couldnt find my music.  did my harddrive delete my music when it started backing up my empty harddrive?  is my music hidden somewhere on my external??

2. when i was backing up my files today, well, i didnt realize it was backing up automatically, i just wanted to put a couple things on that were super large.  after i copied them over, i put the internal hd copies in the trash, but then i went to look at my external and they were gone from there too!! when i threw out what was on my computer, it deleted it off of my external.  does it just delete things if its not on my internal? 

3.  its been backing up my computer for over 4 hours.  why is it taking so long.  it just keeps saying "in progress" how do i find out how much longer itll be?

i am so confused.