Psalms Self-Destruction

We know that "Destruction" is a big deal in Psalms. But it's not just God who's causing the mess. It sounds like the enemies of the Israelites are actually destroying themselves—with their not-so-nice words and their praise of other gods.

Questions About Self-Destruction

1. According to Psalms, how will God's conflicts be resolved, and who will resolve them?
2. Where does agency truly reside in this book? In God's hands, or elsewhere? Do humans have any control over their situation? 
3. Do the Israelites self-destruct as well, or is it just the enemies?