This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
All the probable questions? That could take 20 years to answer, and it still wouldn't be complete. Are you sure you won't settle for a "Top 5" list? Or a few? I know that when I read your question I feel so overwhelmed that I'm thinking I'm going to just move on to the next question. Might I suggest a question like this: "I would like to be prepared to answer interview questions on servlets. Can anybody toss a few my way? Has anybody experienced any tough servlet questions that they care to share?"