The audio files are always converted to the highest available quality which means that'll be at least as good as the audio in the video if not better.
The most common bitrate for the MP3s is 192 kbps, but if the desired video has the better quality available, the MP3 can be up to 320 kbps. In the proces of downloading the song just select desired bitrate.

Bitrate selection

Absolutely not! Downloaded files need to be used only for private purposes and should not be shared or uploaded to third party websites. If you like the song, please support the author and buy it.

Yes, it is possible to download only the selected part of the song. It is possible to edit the time frame on the start and at the end. Just use the "Time Frame" function as indicated on below photo. Start time