Who is Orlick? Why is he upset at Pip's half-holiday? Why does Mrs. Joe become upset?

Orlick is Joe's journeyman. He works for Joe at the forge. While working there, he feels that he should get the same privileges as Pip. Pip wants to take a half day off to run to Miss Havisham's to thank her for her generosity.  Orlick feels that's unfair, and voices his opinion at once.  He says that Joe is favoring Pip over himself.  Because of this confrontation, Joe allows Orlick to leave as well, so it's fair. 

Mrs. Joe overhears this and begins yelling at both Joe and Orlick. She doesn't want anyone getting anything for free.  When Orlick starts calling Mrs. Joe names, like "a foul shrew," Mrs. Joe demands that Joe stick up for her.  Joe was just telling Orlick to watch what he says.  She wants Joe to show Orlick physically who is truly the boss.  So Joe fights Orlick and takes him down with one big punch.  This satisfies Mrs. Joe and only angers Orlick more towards Mrs. Joe.