You will be taking D3 for life. It is not a vitamin but a required hormone for your immune system. You can avoid d3 by spending 1 hour in the sun every day (no sunscreen).
It is not a tablet. It is a geltab that is made with olive oil.
You take the blood test after 3 months, then adjust your dosage to achieve 70 to 80 ng/ml in your blood test.