1. I didn't have to "participate" to airdrops beforehand, as i got them afterwards for supporting right projetcs. But i had to manually acquire them, just like you had to with most of them.
2. I can't remember specifically, few thousand dollars from one of them.
3. It didn't, i was on my way out of crypto at the time and it was right before bear run really started.

One project gave 2 airdrops in 2 different tokens. I sold them right away, thank god. Because i truly loathed the project. Project itself was lucrative to me, but i hated myself for having to wait and listen the lies of their marketing.