"I have a Rolleicord Va II. I would like to have a cable release to prevent any camera shake while on lower speeds."
Good idea, I tend to use a short cable release with the Cord more and more often (unless I loose the cable release while shooting... sigh).
Allthough it´s more of a mental thing - the shake you feel happens after you release the trigger, when the photo has already been taken. Rolleicords and Rolleiflex are pretty good in terms of camera shake.
"What type of remote cable should I be looking for? Will any modern day cable work for this camera?"
Yes, most current cable releases will fit the Rollei.
"Are these cable release fittings all the same -- old and new?"
There are only a few exceptions like old Leicas, Nikons, FEDs that need a special attachment/adapter. But the Rollei takes any of the current cable releases with a standard thread socket.
Get a short one, not longer than 10cm. That will allow you to hold the camera tight...
Since cable releases are easy to loose, i buy them used in bulk at Photo swaps and flea markets - many sellers throw them in for free if you buy a camera or lens, others sell them for 1EUR/item, cheaper in lots of 10 or more. You´ll need them. ;-)