Silver Efex:
The slider bar on the left is deceiving - there are 32 preset B&W (antique, sepia, etc included) and you can create your own.
Color Efex: I can't even try to explain all the crazy editing and options you have here - it's better to just try the trials if you can.
Edits are created in a new layer, so you can still mask and blend however you wish. The edits are done based on what YOU can see. So if you turn off layers you can use these filters to only affect certain things and then turn your layers back on. Makes for some interesting ways to edit.
I've the RAW Presharpening and Output Sharpening plugins too, but I never use them. I find I can do what I want better in PS, but maybe I just don't know how to properly use them.
Edit: Guess you can't see my pointer in the Silver Efex image - I'm hovering over the #1 at the bottom - this shows you all the areas of your image that fall into this light zone to help you make your edits accordingly.