Whitebalance in DPP

I'm having trouble getting my whites balanced correctly in DPP, perhaps you guys have the solution... When shooting small products in a little studio setup, I always put a kodak graycard in the scene to get a good whitebalance. Now here's what I do to set the whitebalance:
- put graycard in scene, make the reference photo
- in DPP, select "click whitebalance"
- click somewhere on the graycard and I can see the colors shifting
- click somewhere else on the graycard... the colors are shifting again?
It seems to me the pipette is just too small. In PaintShop Pro and PS Elements (sorry, no full-blown PhotoShop here!) I can set the size of the pipette, but I can't find such a feature in DPP. Anyone knows how large the pipette is? Is it just a single pixel maybe?

Edit: just searched DPP's help... in two different places, the size of the pipette for exactly this purpose has been specified. Once 1 x 1 and once 5 x 5.... ????

Another thing: is there a way to read the exact color temperature in DPP? I mean: I just click somwhere on the graycard, the whitebalance is set to that, but I can't find the exact color temperature.

Third question: if I set the whitebalance first and than choose a picturestyle, will that shift the color temperature? I.e.: do I first pick the picturestyle and than set the whitebalance, do I do it vice versa or does it not matter at all?

Note: lighting shading seems to affect gray cards in that darker areas on a gray gard will result in different WB then lighter areas, however, if you pick the best lit areas, at least I tend to get correct colors then.

Meanwhile I can answer number 3 which is yes you should change style first, then set WB as changing style will affect color (noting that if you change the style back it will return to what you had).

That is about the limit of my ability to help with DPP.

I would suggest junking the grey card for studio work if your lights color temperature is reliable across intensity settings. Instead one should point the camera at your light source/diffuser and take a grey image of that and use that to set a custom white balance. By balancing off the light source you remove a layer from your white balance calculation which in turn removes any imbalance in the card. Albeit, this does not account for deviations in tone due to fill light from ambient sources.

This also has the side effect of setting the color temperature to a custom value which most RAW converters should display for you.

some thoughts,

Sean