Ricardinho is a average player, wouldn't add that much on our team. He played on World Cup, but he was the most contested player on Brazilian Squad by the fans.
Recently he gained an election between brazilian players as the "most hated player" in front of Romario, Edmundo and other players knew as "bad boys". 2002 he left Corinthians to play on their rivals Sao Paulo. Did nothing there, and when left Sao Paulo, he went to play on Santos, another rival. In the end of his contract he left Santos to Corinthians again, where he's now.
I don't know so much about Felipe but if he know how to dominate a ball he's better than Legrottaglie...
About Kerlon, he's injury prones, he got about 2 serious injuries in a short time.