Definitely. The Joker has a long history in comics and is a staple villain. His character and storylines often evolve and branch out across different comic series and story arcs.
Well, it depends. 'Wanted' might refer to a wanted criminal in a comic or a desired item or ability. But without more context, it's hard to say for sure.
Riverdale has no connection to DC Comics. It's based on the Archie Comics universe and has a distinct style and plot separate from DC's superhero world. The characters and storylines are completely different.