You don't want to be caught up creek without me, Or be left adrift with just the board I come with, You need two of me to play table tennis, I'm a classic first movement you learn to swim

I spend my life on someone’s wrist, yet my name is always looking elsewhere.

When done to yourself, you arrive with no lethargy. When done to a device, it forgets its memory. Press a pencil into me on the back of your calculator, Not a permanent break, but more of a see you later.

My first is a place to rest your butt or your head. My second keeps things safely shut instead. Together, I protect what's yours. What am I?

I drink without teeth, I feast without a bite, I hide in the shadows, out of sight. I swallow the waters from a rainy terrain, Or sap your energy like a vampire’s game. I take what flows and carry it away, From drops in a sink to the energy in your day.