The main difference berteen Spacecraft and VB is that Spacecraft gives a simplified version of the underlying Orbiter's API to the user, while VB tries to make the entire Orbiter API available. This means that the best reference for VB functions and parameters are the Orbiter's API themselves, which I strongly suggest to look at for better reference of the various parameters. In this particular case the best way to create a parachute is to define a variable drag element, as gattis correctly guessed. From the Orbiter's API docs (which can be found in the folder /Orbitersdk/doc/API_Reference.pdf or API_Reference.chm, the definition of variable drag elements are:
So you need to create a variable drag element, bind to an animation, define the reference which is where the drag force applies (i suggest fake symmetrical coordinates) and the factor which I suggest to experiment it a bit with. I haven't checked, but I am pretty sure that in the SC4 docs there si the definition of how speedbrakes work there, so it shouldn't be hard to reverse engineering the factors. Give it a try and in case get back here and I will look into it.
For the dCl I suggest you to look into the Orbiter's API at CreateControlSurface function. there it is defined as
I honestly can't remeber now if the shift is intended as a change in magnitude of the lift or as a position shift of the lift vector, I should make a test because too much time has passed and I can't remember it. But it should be written down in the docs or someone here who has confidence with the OAPIs can surely be helpful.
If you need further explanations feel free to ask!