studies show 2-5 grams is all that is needed; this is of creatine monohydrate. Other creatines are essentially creatine with a different delivery system. ex kre-alkalyne= creatine & baking soda, creatine malate= creatine & malic acid. These are to aid in delivery so that the need for a carrier is fulfilled. Sugar is conventionallly packaged w/ monohydrates but protein is I believe 95% effective at aiding creatine absorbsion.
Creatine increases ATP your body's currency for cellular energy; take some before workout and get a better work out, take it after and recover better.

Generally supplements are absorbed better post workout especially when aided with proteins due to increased protein synthesis, so if anything take it post workout. For best results take ~2grams before and 3 or so after.