To: dg67f
Dear user,
Thank you for all the suggestions, I will surely pass them over to our developers.
| dg67f: | 
| create audio file only, by choosing the audio track (from main video track or secondary audio tracks) to produce | 
It is possible in AVS Audio Editor:
http://onlinehelp.avs4you.com/AVS-Audio-Editor/
| dg67f: | 
| crop a video clip in the main video track, with or without keeping the original aspect ratio | 
You can select the aspect ratio for your video project in AVS Video Editor: press Edit on the top toolbar - Aspect ratio.
You can use 
Zoom effect to crop your video.
| dg67f: | 
| 5.1 audio track in video production | 
At the moment it is possible to maintain all channels for audio when creating WMV, MP4, FLV and MOV file format video files. 
Please let me know if I can be of any further assistance to you.
Kind regards