Diane's pusher(the kid) is selling drugs in this episode... he's also the lookout kid for Cleatus in the episode 'Cousin Cleatus'.
When Willona is reminiscing about her prom, James makes a crack about the fact that she graduated in 1948, to which Willona shoots back that she was the cutest four year old at the prom. This was somewhat true due to the fact that Ja'net DuBois, who played Willona was actually born in 1945 and would have been close to that age.
Uncle Bens is a brand of rice.
It is presumed that, when Diane flees out the motel room window, she becomes a prostitute to score heroin. Her character is never mentioned again.