Shortcut to add fade-in

I don't know how much this speeds things up, but you can assign a keyboard shortcut that will put a default fade at the start of a clip, although you'll have to drag it back to where you want the fade to finish.

If you go to Edit>Keyboard Shortcuts>Clip>Fade In Normal, you can assign a keystroke to this - for instance choose # which doesn't appear to have anything else to do. Select it and save it. Now, if you highlight a clip in your session and hit the # key, it will place a default fade at the start of it. If you now hold the Shift key down, you can drag this back to wherever you want the fade to be complete without the shape altering.

Personally I don't think that's any quicker than just grabbing the fade handle and pulling it to where you want it, with the shift key held down, but that's the closest you will get to a keyboard shortcut for it.