I know bout the kid that wants you to slay an orphange worker ....but is there another way to find it?

No.

The only way to initiate the DB questline (whatever your intentions toward the faction) is to do that quest. Otherwise you will have no contact with them, aside from random encounters with nameless generic assassins who spawn from time to time.

Nope, you will have to kill the target to join the DB. that's the only way.

I really don't like that it was handled this way, and I honestly think Oblivion executed it better.