I had some drain issues last week too. Nothing like what you're describing, but I isolated the problem to the Google Fit and Google+ syncs. I don't think you need to outright disable Google Now just yet (honestly it's one of the best things about the Android infrastructure IMO). Try unchecking those sync options within your Google account first. If you don't back up your photos via Google+ Photos, you can unselect that too, but at least make sure that you have it restricted to wifi if you leave it on.
I agree about the Power Toggles tip. Think that's what is getting you there.
Also, what launcher are you using? I can't tell if that's stock or Google Now. If it's Google Now, I've found that it's incredibly laggy on this phone due to the 1GB RAM. Constant reload after almost any app load and minimization. Use Nova Launcher or stock.
BTW, it's not a bad thing for your phone to have a lot of RAM in use. That's how the Android OS works. Essentially you don't want a lot of free memory b/c it means you don't have quick access to your apps.
My personal tip: forget Clean Master. You shouldn't need it on this phone. It's lightning fast by itself and is just taking up RAM that could go to something else.