Just found a TON of secrets, found all luigi exits except ones that are on levels that have no yellow dots(because of the faint L).Found all world 1 kooplings, and (unsure) all pipes, purple, yellow, red, and blue.There seems to be a theme with secrets, there are secrets within secrets.
SirArsen
Just found the secret exit in 1-1, found every secret in world one except one koopling, i'm pretty sure I know where it is though.