Mardi Gras

I chose Mardi Gras as my topic for the I-Serach paper. I follow the local Mardi Gras every year as they go from house to house chasing chickens, dressed in thier costumes and begging for money. I would like to know more about this holiday. Why do they dress in costumes, chase chickens and beg for money? I would like to know why the some people celebrate Mardi Gras different than we do. Why do some towns have parades and throw beads instead of chasing chickens? Is Mardi Gras only celebrated in the Louisiana? I have many questions about this holiday that I hope I can answer through  proper research and study.