How many teams can I add in the "My Teams" area?

The limit is currently 100 teams.

How is "Average Age" calculated?

It's the average age of the players we project as your starters (QB/RB/WR/TE only)

Does the Team Analyzer's "Team Score" take "rebuild" mode into account?

No, "Team Score" is only being calculated based on your team for the CURRENT season. However, if you are a dynasty team that's in rebuild mode, the "Conclusion" area of the Team Analyzer page may speak to that and/or the future outlook for your team.

How is the Playoff Percentage calculated?

The percent chance of your team making your league's playoffs is calculated using many different variables, including (but not limited to):