Stock/ETF Benchmarker

What does the Performance Details window in the Benchmarker tool show?
How do I compare my portfolio's performance to an index benchmark?
Why are some of the symbols in the Benchmarker Performance Details window displayed in italics?
What does the Portfolio vs SPX window in the Benchmarker tool show?
Can I filter the symbols that are shown in the Benchmarker Performance Details window?
What does the Top Contributors window in the Benchmarker tool show?
What does the Sector Contribution window in the Benchmarker tool show?