Need Advice For Budget Traveling by Bus

I need help with traveling from Buenos Aires to Brazil. I would like to go to the Falls on the Argentina and Brazil side (Foz do Iguacu) upon leaving Buenos and then traveling along the coast of southern Brazil starting in Florianopolis and head to Fortelaza in the north. Could someone , please tell me the best bus route to take upon leaving Buenos Aires. Should I go to the Falls first or to Florianopolis first and how many hours will I be on the bus. I appreciate any help.