Is it fading in and out at the beginning and end of each clip or somewhere in the clip?
I'll tell you both anyway.
To fade start/finish, put your mouse over the top corner of the clip and your mouse cursor will change, click, hold and drag.
To fade in and out during a clip you need to insert video/audio envelopes. Select the video or audio clip by clicking it, then go to Insert, then choose whatever envelope you want. A bar will appear in the selected clip. Right click on the bar to add points. Event Velocity is for speeding up/slowing down video.
Aspect ratio is different screen settings, sort of, but I'm sure
wikipedia can tell you what it actuall does.
Hope that helps.