>Few quick questions. Does LR 4.2/ 4.3 exist and if it does >can one buy the update without buying LR 4?
4.2 is out in final form and 4.3 (which contains the full set of D600 color profiles) is available as a release candidate from labs.adobe.com. Not too surprisingly, you have to buy LR4 in order to update to 4.2 or 4.3.
Secondly how is >the experience with the these updated versions? Any problems >with the raw processing?
In my experience, LR 4.3 works very well with D600 files.