Are there any free alternatives to finder?
I don't know the good free alternatives, but PathFinder is the best file manager I have ever used, and probably one of the best desktop apps I've ever used. The features I use most


Bookmarks and multiple tabs
Multiple panes 
Side panes with folder shortcuts
Drop stack


Most importantly, it's not clunky (relatively) and is very reliable. It was worth every cent I paid for it.