Are you using Windows or OS X on your home computer/laptop? You can sync the 920 with your iTunes library through software called Windows Phone on Mac OS X very easily. It automatically detects your iTunes library and syncs everything across; pretty much just like iTunes. I'm not 100% sure how you sync it over Windows, but some quick research will tell you how.
As for music; the 920 comes with an awesome piece of software called Nokia Music. You can sync music all day long for free; I wrote about that in the original post. Im not sure about last.fm (I dont use it), and I guess thats something that you are going to have to decide on.
Overall, iOS still beats WP8 for sure with Apps, thats a given. But, WP8 is advancing very quickly and there are new releases literally every day. There is a small compromise with switching, but if you are as bored as iOS as I was, it's worth it.