There is almost nothing to do. Are the two versions of DW on the same computer? If so, when you install CS6, it should pick up the site definitions and will recognize all of your old sites.
maybe I do not understand your question correctly, but why should that be a problem when you open your files instead with CS4 now with CS6, with the best will I find hard to envisage a problem. You can continue your work exactly like before.
Yes, that is what is supposed to happen. However when I open the files all the design time implementation was lost and the site configurations were lost. I am in the process of restoring them manually. Not a lot of work but just annoying.
