That set's the etags.
And this part identifies what set it (can be changed) Header set X-Powered-By
Run a test at
http://gtmetrix.com, click timeline, expand an element and you will see details about that request including X-Powered-By
No, it doesn't require enabling friendly urls in the admincp. You can still take advantage of the seo friendly urls by selecting this option in your admin cp.
Mod Rewrite Friendly URLs