1. Snoopy and Woodstock dressed up as Pilgrims to because pilgrims started the first thanksgiving and it was about thanksgiving.
2. It's ironic because Peppermint Patty had just gotten mad because there wasn't a real meal of what she wanted, then as soon as they left snoopy and Woodstock ate what she wanted after she got mad.
3. If he would've been more assertive there wouldn't be a problem because Charlie would've spoke up against Peppermint Patty and told her he wouldn't be home.
Explanation:
I just did this yesterday and made a 100% so i hope this helps!!!