You'll be happy to know that both of these requests are already possible, thanks to plugins.
- allows you to crossfade between tracks in the playlist in realtime. It is pretty limited though.
SqrSoft Advanced Crossfading Output
- allows you to crossfade two songs, the one Winamp is playing and the next in the playlist. The crossfade is made by analyzing sound level of the last seconds of the song to determine the best mix point, applying the level envelope curves to the beginning and end of the tracks. You can set different crossfading parameters for normal crossfade on track end and when you skip the track. This includes the mixing length so you can set the mix to 10%, 20%, etc. This plugin includes a Gap Killer that eliminates the silence or any sound bellow the trigger level, this is applied to the start and end of the track.
- shuts down your computer when WinAmp has played all the tracks of your playlist. That's especially useful when you want to listen to some tracks while you're in bed and you're too lazy to get up once more just to switch off your computer. Starting with v0.3 you can also you it as an alarm clock that wakes up your system from hibernation mode in the morning.