Reply to Record only in .Wav?

Long story short my mates keep moaning my mixes to big in file type as i always record as .wav in S4 and also when doing vinyl only mixes etc,

A) In traktor can you select the recording to be an mp3 instead of wav as i cant see any option?

B) If not whats best program to change wav to mp3, dont want any fancy stuff just a really user friendly load program open track and click convert. I though Mac had something built in ( i may be wrong) and cba to reinstall logic just yet!

Thanks