Hi. Do I understand correctly that you are having problems finding .wav files in the database which you synced via iTunes? If so, then I think there's not much of a way around that. From what I understand, the Apple firmware indexes files in the iTunesDB and doesn't directly read the metadata from the individual files. I don't think that .wav files have a well defined (standard) metadata format for storing such attributes as artist, album, etc. As such, your .wav files will probably be listed as Untagged in Rockbox's database. Probably the easiest solution would be for you to convert WAV to ALAC. This will save space and provide the ability to attach proper tags to your files. Of course, I am making some assumptions here:
1) That you want to store these songs in a lossless format
2) That you wish to continue using iTunes to sync music to your iPod
*I split the topic for you. Please start a new topic for each distinct question.