I've had that happen every few weeks or so. AFAIK, it's either happened after installing a new app or after blocking an app from running in the background. Each time it happened, I powered the phone of & back on and the problem went away.
That was a complicated way of saying:
"Open all installed applications one by one and close them by pressing the back button. Some might be waiting for your input[.] Open those too and close them systematically".
Good idea. I have occasionally battery drain that could be related to your...
The multiple entries per song issue isn't SD card related. My 920 had the same issue. The various suggestions on the various forums didn't fix anything.
I ended up deleting all the songs using the Phone's user interface, then re-synced all the songs.
The default PDF app shares documents by uploading them to Skydrive and sending an e-mail with a link to the shared document. I don't think that will work with your printer.
As does different speedtest.net sites. Speedtest seems to think that servers that are geographically close are the best for testing. That leads to poor results. Physical 'nearness' is not as important as logical network 'nearness'. One might be best choosing a server that is fewer network hops...