Haven't tested extensively yet, of course, but so far, so good.

May even install on the iMac.
Do you have CS6? If so, does it run?
Yes - it runs fine, from what I can tell. I've had no issues in Photoshop CS6 - forgot I was even running a new OS.

I will be one unhappy camper when CS6 ceases to function, as it no doubt will at some point after some future update. I LOATHE Adobe's subscription model and will likely try my darnedest to find something else to use instead. Unfortunately, nothing out there is quite there yet - though there are many apps getting much closer to being Photoshop-killers. InDesign is another kettle of fish - there is no really good substitute for it, and I sure as heck am not going back to Quirk. Er...Quark. However, there is hope. Serif, who have the Affinity line of apps (and a great photo app from the looks of it - I've yet to try it) have Affinity Publisher set for beta release at the end of this year.
https://affinity.serif.com/en-gb/about/ - they offer trial versions as well.
http://www.techradar.com/reviews/pc-mac/so...-1295010/review