1. Not without some kind of specific reason! It's not what any pro athletes do. Consistency wins. I would say there is a little bit of "woo" in the general crossfit training world, though there seem to be some very smart people too.
2. How could we know, since we only know that you want to build muscle. However, since there is no crossfit nearby, I'm going to go out on a limb and say, "no". Also, crossfit is probably not the best possible method for muscle building, even according to crossfit people I've talked to.