The thing to keep in mind, though, is that Windows Phone is not Android. You do not NEED to manage tasks. Let the OS do it. It does a fine job of it. Your tasks will not run amok here. The wild west is branded by Google, not Microsoft. Yes, it was under Windows Mobile - just one more thing that makes me agree with the podcaster that I once heard say, "Android was born a bad copy of Blackberry, grew up a bad copy of iPhone, and will die a bad copy of Windows Mobile."
Let the phone manage tasks, while you do what Microsoft designed the phone for - get in, see what you need to see, and get out.
The way it works, with the exception of apps that are allowed to run in the background, like Nokia Drive, for instance, is that if an app is not running in the foreground, it is not consuming any processing time at all. NONE. It is sitting in memory, idle. It was suspended. In WP7, five apps could be suspended, and IIRC that was bumped up to 7 or 8 in WP8. If you have more than that in your back history, the oldest will be tombstoned - the tombstone process run, assuming the developer wrote them into the app, and the app removed from memory. If the OS decides that it needs more memory for a currently running app (which is also limited to how much memory it is allowed to consume), then the OS can tombstone suspended apps on its own as well.
There is no need to manage your tasks.
There is one exception. And I will throw this in there pointing the finger at myself. If you're OCD, like me, your back button will wear out way before the start button will. Get it? 
You're welcome.... And regarding out-appling Apple, I think I speak for a lot of us when I say that we all felt that Microsoft was well on its way toward this target two years ago. They hadn't made it yet, but they had a good start, and have made great progress in that two years. I'm glad to say I was in on the ground floor. 