Where should my feet be while paddling?

I was riding a shortboard today for the first time and I didn't really know if I should have my feet off the tail or right on the edge of the tail or what. I had my feet right off the end of the tail, but the waves were too big for me today so I didn't get many rides, so I couldn't experiment much.
Also, on the pop-up, I have my hands on the rails when I pop-up, but I'm not sure if I should have my hands on the top of the board. Is it easier or faster to get up that way?
Also, on the pop-up, I have my hands on the rails when I pop-up, but I'm not sure if I should have my hands on the top of the board. Is it easier or faster to get up that way?