Transitions, provided you stick to the ones recommended in the user manual (bare bones) and especially if you know what you're doing, should work. They will, of course, need tweaking. According to the user manual, you should be able to include keyframed audio levels in the EDL. It's on page 139, volume II, for FCP 6.0. I haven't tried it. It might be one of those things that should work, but doesn't.
For my purposes, I only needed cuts, but it's good to know the EDL can theoretically handle more than that.