You need to look at your external editing options in LR. It would seem you are editing in 16bit (best for maintaining quality) which accounts for the greyed out menu options.
If you really need all the options and filters set these preferences in LR
Edit>Preferences>External Editing. On this dialogue you can select Colour Space, Bit Depth, File Format and File Compression.
Alternatively in CS3 (You will need to do this on each image)
Image>Mode Select 8bits/channel
I hope this helps.
