Yes you do still need the Calcium. With the MVB you need the Calcium with No Phosphorous and No Vitamin D3.
I also just switched over to an MVB and had to replace my old Calcium w/VitD3 to without. It has a much grittier feel to it. My beardie is still trying to get used to it.
Yes! Please do not continue using the calcium with D3 once u start using the MVB. The MVB bulb helps with D3, that is why it is not needed with this light. Too much Vit D3 can be toxic to your beardie.