I concur with THobson on the ogg part...
There is no lossless audio/video compression (and most likely never will be)...
Uncompressed wav sounds always better, maybe not with OFP since it takes OFP a while to go through the wav before it plays it = wav causes lag..
But IRL..
Also, ogg is much better than mp3...
I ran some tests and with some non-hifi equipment I really couldn't hear as bad quality loss with ogg than with mp3...
I'm not a graphics guy but yes, alpha channel is used for masking areas of the pic that will be visible, partly transparent or completely transparent (shortly put)...
You can open p3d files with BIS released tool Oxygen (O2 for short) if the models are a format O2 can read (MLOD)...
For example the models in the Data3D.pbo are in ODOL format which O2 can not open.. There's a tool called ODOL Explorer (3rd party) with which you can open the ODOL format models and if you like, convert them into MLOD for O2...
The ODOLEx does screw up the models a bit but those are tiny things you won't even notice if you are not a modeller...
(sorry)I'm too lazy to find any download links.. Search through the official BI Forums
(/sorry)