Can the pixels of my 60 Hz L90D+ change up to 60 different colors in a second? To my understanding 60 Hz would be 60 different frames per second. Then the response time is just the delay after the monitor is told what do by the video adapter? My monitor is rated for a response time of 8ms.
Correct (well, I would write it more as 'can change colors up to 60 times per second', but that's picking at nits). Correct. I don't think so, but I don't know. (respectively to your questions, of course)
I've heard some people saying something about 85hz rates on some, but I didn't look into it.
Read Tom's articles about LCD monitors for the details on what 8ms really means.