Finance experts/CPAs please help me on this topic. My German boss is mentoring me and I find some of our topics difficult. I am interested to learn though. I think he expects me to know these things but I really don't

1. Please explain in the simplest manner: short and long position. Why is it that in the B/S a short position is reported as negative and a long position is positive? Is this an absolute rule?

2. What is the difference between a trading book and a banking book?

3. How are debt securities and money market paper connected to Fixed income securities?

4. Reverse Repos - Please explain

5. What does my boss mean when he says before netting of short position? We are looking at Gross amount of fixed income securities

IF anyone knows a website where I can read up on this topic, I would really appreciate it