Running with GPS Watch Guide

Help me get the most out of my GPS running watch.

My watch: [brand and model]
Experience level: [new to watches, some experience]
What I currently use: [features I already use]
Training goals: [what I'm working toward]
Confusion points: [features I don't understand]

Please explain:
1. Essential metrics to track
2. How to use heart rate zones
3. Setting up training features
4. Interpreting training load/status
5. Pacing features for races
6. Interval workout programming
7. Data fields to display
8. Syncing and analyzing data
9. Common mistakes with watch training
10. Features I might be missing