I'm not current with the comics... Has his character been introduced yet, as had been planned?
I don't believe Daryl has ever been planned for inclusion in the comics. The character with a crossbow on a cover in the lead-up to issue #100
was an entirely different individual - and was not remotely friendly.
Can't be sure, but I've been under the impression the Merle was indeed a character from the comics, but Darryl was created for the show.
Both Dixon brothers were created for the show.