Sliding Mirror Closet Doors

I have a few questions about sliding mirror closet doors. I am in the process of installing new carpet in the bedroom. I previously had old heavy wood sliding doors in the bedroom. I have decided to change out to a mirrored door. This door weighs about 20 lbs. I have hung the new mirrored door on the old track no problem. My first question is this new door came with a bottom track which my old door didn't have. Is it really necessary to use this track? My old door didn't have a bottom track. I was just going to use a door floor guide to keep it from swaying like the old door had.
My 2nd question would be if this track is necessary can it be installed over the new carpet or should it be attached on the wood floor & carpet installed around the track?
I really don't like the look of the track & wondering if necessary.
Thanks