Question: Why did Shine not pay back the firm the $10,000 out of the $100,000 he got back?
Question: Charlie rings Lucinda's workplace and they put him through to her. But later he finds out she's just a temp called Jane, how does that work?
Answer: The operator put him through to "Lucinda" on the phone because there is a REAL Lucinda that works there and Jane (who posed as Lucinda) was her temp who filled in for her supposedly when Lucinda was away. So the operator simply patched Charles' call to Lucinda's office, and Jane answered. It was either lucky for Jane that Lucinda was away at the time, or maybe Lucinda was away on business for a given amount of time, and Jane took advantage of that.
Answer: I assumed that that Charles Shine did not have time to return the money to the work account before his boss discovers it is gone because the banks would have been closed when he was at the hotel and retrieved the briefcase with the $100,000. Granted, prior to this he asks his boss for a check for the commercial expense, so it might have made more sense to ask for a transfer earlier because a check implies that he did not signing for funds and could not have embezzled the funds. How he stole it if he did not have access to the account, I do not know.