Cubase + Ableton Live questions!

Hi all, I am new to Cubase. These days I mainly produce within Ableton Live 8. Do any of you out there combine Ableton Live and Cubase?
If so, how?
Do you compose in Cubase and manipulate in Ableton? Compose in Ableton and mix/master in Cubase? Please share!!
Are there functions that Cubase excels at, and vice versa for Ableton? If so, what are the functions?

I am hoping that I can get some realistic sounds out of Cubase. Ableton Live is great at the electronica side of music. I got Groove Agent 3, Halion Symphonic Orchestra, and Guitar Rig in hopes of using real-sounding instruments (and real instruments, like my guitars).

Just wanting to get a better handle on the role that Cubase can play in my music production and workflow. It is the first full-fledged DAW I have ever used (minus Cool Edit Pro, if that counts, but it was my first program and here I am 10 years later). Your input, advice, stories, or techniques are MUCH appreciated… I am very excited to put Cubase to work for me!