My cats miss me a lot when I'm not home. Which is why I only go out to work or important errands. Which is why since I've had cats I don't have a life anymore.
They show they've missed me by meowing pitifully when I come back in what sounds to me a reproachful "blah blah blah and you left me here to die!" Heck, cats miss you even if you so much as spend some time in the bathroom on your own.
And no, they don't know if you're coming back. I think more than happy, they're relieved to see me back. When I used to go on business trips, that's the impression I got.
Before adopting them, I used to go out on tours (just a few hours, mostly Jerusalem and the Galilee) 1-2 times a week, it was my hobby. I miss that. If my cats didn't miss me, I wouldn't be confined to the apt., I'd still be able to travel.
My strays, even when not hungry, won't leave my side.
I wish cats didn't miss us.