Hi there!
I'd appreciate some help from you experts in steganography.
1) If I hide some PGP encrypted data in a gif, jpg or wav file will there be any tell tale signs to the naked eye of an expert? If yes, what are they?
If you stego too many bits in a figure, it may become apparent.
2) Would it better to hide the data in a jpg with black and white image rather than a color one?
24 bit color has more data, therefore its easier to hide random data.
3) Are there any tools at the moment to expose (not crack) the hidden encrypted data? If none. are there tools in development?
Not really. If you make sure there are no predictable headers, and use a good encryption algorithm, it is almost impossible to tell the presence of a hidden file unless you compare a file untouched with the one with data in it.
If this appears twice please accept my apologies. I didn't see the first posting and so I assumed it was lost in transit. Please email replies to me directly if this is off-topic. Thank you.
Makofi