That does seem a little odd. I am running Adobe Creative Suite 3 on my MacBook Pro and I am running Mac OS X Mountain Lion Developer's Preview 2. I have never had an issue with it, I started out running it under Mac OS X Tiger.

Is the installer not working? What message are you getting? Is it something about 'Rosetta not supported'? Or are you getting something like, "Licensing for this product has stopped working." Adobe has several fixes available on their website to get the installer running.

I think it would depend on what you wanted to do with your photos. The EF-S 18-200mm gives very soft images, the focusing motor tends to noisy and slow, and lens creep is an issue. The build quality is mediocre at best.

From looking at the other lens you have, you probably would not be satisfied with the results from this particular lens. I have also been looking for the 'perfect' carry-around lens for the small-frame Canon bodies. I have settled on the EF 24-105mm f/4L IS USM as my main lens. I know I don't have much wide-angle coverage but that really hasn't been much of a problem for me.

Canon changed their RAW format a while back. The extension is still CR2. The change came about the time of the release of the Digital Rebel T1i (500D). A plug-in for PhotoShop CS5 can be downloaded from Adobe.