Front derailleur replacement
In my personal experience I've found that front derailleurs make little difference to the shifting. I have noticed very little difference between my new Ultergra, my 15 year old daily Tiagra and the 2nd hand supermarket bike to leave at the train station in the morning.
Front derailleurs should take very little time to set up as they are simple brute force devices. Poor performance comes from sticky pivots after years of neglect and generally worn cables.
If you are set on replacing I've linked to the Sheldon Brown article which should give you some details on how to identify what you have so you can find something similar to replace with