Android 4.2+ Multitasking and recent apps

I've been enjoying my Nexus 4 immensely since I bought it, but since being a convert from iPhone I had a few questions about multitasking and the recent apps list. I know that on iOS the apps usually pause themselves when you quit them unless they use one of the background API's. So, does Android 4.2+ have true multitasking like or is it more like iOS?

Secondly, I know you don't necessarily have to use task killers with Android, but what's actually happening at a system level when you swipe an app away from the recent app list? I don't want to unnecessarily swipe apps away, as I remember reading somewhere that it can take more CPU cycles to open an app than to keep it running.

Sorry in advanced if any of my technical info is incorrect, just going with what I've read before and trying to make sense of it all.