Photoshop CS4, CS5 and CS6

I've just upgraded to Photoshop CS6. I still have applications for CS4 and CS5. This includes Bridge, Device Central, Extendscript Toolkit, and Extention Manager. Each version has one.

Can I get rid of all relating to CS4 and CS5 now that I'm using CS6?  Any downsides?

I also have some plugin programs like the Topaz Suite and now Perfect Photosuite 7. How do I migrate them into CS6?

Thanks for any suggestions and help.

Bob Collins