The multiplayer thing was addressed by the devs on the bioware forums. Playing multiplayer just makes it easier, but there's more than enough content in single player to max out your galactic readiness. I haven't even tried multiplayer in the full version yet. And I personally haven't had a problem with the import system, and I've imported from ME1 all the way to 3 on XBOX.
I don't know how I feel right now. This is still one of my favorite game franchises. I played ME1 and 2 countless times, but I just don't think I can play this one again. Which is a shame because it was really good. The ending just kills the entire experience. I guess I'll just wait for word from Bioware. Supposedly they tweeted that there's going to be an announcement sometime in April about an upcoming DLC or expansion. Hopefully it has something to do with the end.