Rem's gender isn't really confusing (and also it doesn't matter). People just called Rem "him" because it's pretty damn hard to tell what she's supposed to be, being a monstrous god of death and all. And she simply didn't bother to correct Light. But she felt it was important for Misa to know, because she's the one most important to Rem. That's how I see it anyway. I often get called "miss" on the phone at work, because I have a very high-pitched voice, and I don't bother to correct anyone unless they specifically ask again.
That said, the last couple volumes really show what the manga does better than the anime! For quite a while they were pretty much exactly the same, but the Yotsuba arc profits from some more in-depth explanations, especially of everyone's thoughts. It really helps the story as a whole. And the art is of course fantastic! I swear, somehow manga-Misa looks cuter than the anime counterpart at times.
Can't wait to see the solution, even if I already now it from the anime.