Re: apps running, but i got "no recent apps" screen.
A blank recent apps screen doesn't necessarily mean that you have no apps running--it can just mean you swiped away all of the recent apps. Some apps, when swiped away, won't completely close (like Google Play Music, for example, if it's busy playing a song). If swiping away an app did in fact force close it, it might have restarted automatically--but that doesn't mean it shows up again in Recent Apps. My understanding of the Recent Apps list is that it's composed of apps that you recently opened, not apps that may have been automatically opened in the background by the system. It's not a "running apps" list. That's in Settings>Apps>Running.
Remember, with Android, there's always going to be some app open in RAM.