This website has information recently published by FINRA which shows daily short trading volume as well as total daily volume of shares traded.
You have to scroll down and click one of the links at the bottom of the page.
www.finra.org/adf/regsho
I don't short and currently have a cash account. I would imagine that If you have enough cash available that a cash account would be fine but I'm not sure. Best to talk to your broker.
News 
Market Data 
Discover 
