From what I read, 9006 bulbs should fit into the same socket as a 9012. The 9012 was originally based on the 9006 (and 9011 originally based on 9005), just upgraded/better/brighter bulbs.

9012 into 9006 housing = trimming of one 9012 tab to fit.
9006 into 9012 housing = some sites say no trimming, others say very slight trimming of one tab.

Comparing halogen to halogen, a good quality stock wattage 9006 bulb puts out around 1000 lumens. A good quality stock wattage 9012 bulb puts out around 1800 lumens or a little more.

6000k will generally give a slight hint of blue. I always like to use RetrofitSource's reference image.

 

Just to update anyone following this thread, I was able to install 9006 bulbs in a 9012 socket with some minor trimming to the tab.