Not sure if this is true ou not,but i think i'm correct there was an episode in which The Tommy(Kids suivant Door) cameos.

Nope; Tommy, nor any other KND operative, made an appearance on Ed Edd n Eddy. They weren't much for guest stars (not that that stopped THEM from making cameos on other shows).

I don't believe so. no additional characters from Kids suivant Door ou any other montrer on Cartoon Network at the time made any appearances in the show.

No I do not remember and I have an amazing memory