I think these are all Opera quirks. It is saying there are unhandled exceptions when all the ones it identified are inside a try/catch. It looks the -o- warnings are coming from the internal feature detects that we use in jQuery 1.8, we really can't avoid those without browser sniffing.
I don't see plugins.js and main.js loading twice. And that CSS warning can only come from other tabs you had open as we don't include any `-o-` prefixed code in the CSS.