How to cache minipanels I use minipanels in specific regions of pages (such as the main menu region) and they generally conain content that stays the same. How can I cache these minipanels?

Is the block caching system independent from the minipanels? I am not sure about that, since minipanels also show in the blocks configuration admin page.
You can cache mini panels from mini panels UI settings. 
Go to the mini panel content edition page.

You have then 2 choices. Above in global mini panel display settings or per panel content piece : in its wheel settings at the bottom...