I've read back in the day that the reason there aren't any 12 bit pic's is because it is difficult to keep the noise from the micro away from the ADC.

Now they have new flash pic's with 12 bit ADC. Are these chips really capable of a solid 12 bit result?

If so, can you suggest something similiar to a vanilla 16F876 that would be good to start with?

In addition, I would like to use an amplifier configured as a voltage follower/buffer to allow for higher input impedences. I'm just measuring DC signals and would appreciate some suggestions for a low power multi channel amplifier.

Thanks,
Steve