Equalization in the purest sense makes the sound equally strong in all frequencies, by boosting or cutting certain frequency components in a signal.
There are several effects which deal with the manipulation of the dynamic range of an audio signal such as compression, expansion, limiter and noise gate. These effects work in similar ways to improve the quality of audio.
Chorus has now become a common effect. As with most effects it was initially used by guitar players wanting to add complexity to the sound of the instrument.
Obviously it is important to change your strings once in a while. It is typically recommended that you do it at least every 6-8 months if you really want to have the best sound your violin can give.
There are several aspects you have to take into consideration when choosing your strings, amongst which the most important are your playing style and the instrument’s qualities. In the end, however, it all depends on the sound you want to hear.