I use a three techniques for lining up midi with audio:
First, aforementioned, In Place Editor. Very handy, but not always that easy to use I find.
Second is 'snap to cursor' where I use the project window to line the cursor up with the audio, then in the midi editor I snap the note to the cursor. Good for the odd hit in a film or video sound track but not so good for loads of hits.
Third is to use Warp Time to change the project tempo to fit the audio you wish to align to. Then I'd use quantise in the midi editor to make the midi follow the audio. Works a treat, and saves me playing my midi in time as well
As for editing two things in one editor, I thought this was only for midi, not audio... I'd definitely welcome a split panel editor, or an overlayed/mixed audio/midi editor. +1 please Steinberg.