One of the first things I did when I got my Volt was switch to ART. I soon found out that my Amazon app was crapping out every time I opened it, so I unfortunately switched back to Dalvik.

On another note, my previous phone was the ZTE Awe running Cyanogenmod 11 and ART. Switching to ART was a noticeable difference in both battery life and performance. It ran smoothly, and all my apps behaved properly. I believe the Volt has a few more bugs that need to be sorted out before it's ART ready. Let's keep our fingers crossed for an update.

 

Not if you use the prerooted ROM on here to update.

 

No, just enable it in Developer Settings. Just make sure you have a good bit of battery life. It can take a while to switch over if you have a lot of apps installed.

 

Not USB debugging, but follow this guide
http://androidforums.com/showthread.php?t=872005