@MissTrips, thank you for gathering all this information. Your party guide is incredibly helpful.
I threw a Black & White Party for the first time last night.
When the Listen to the piano requirement appeared, I just ignored it and got a gold medal anyway.
For all of the social events (including dates), I've been able to neglect trying to complete just one of the requirements (just not the main one) and still get gold.
Regarding birthday parties, I've never gotten anything for a gold birthday party though I've thrown many.
I'm still afraid of trying the weenie roast, lol.