I don't play covers but I do like to get different tones. I set my Valve Junior volume on full then run a tuner, wah, octave fuzz and reverb/delay. To get clean sounds I have the middle pickup of my strat set way down in the pick guard, so less signal = cleaner, if you can't do that there is always the volume.
If you can't turn the volume up full for distortion (and you have master volume), stick a boost pedal on top of the amp and run the guitar through that into the amp.
Personally I wouldn't say you need chorus, though you probably listen to a lot of stuff I don't.