The rest of what you wrote sounded reasonable to me, but the above quote seems wrong to me. Iodine tablets have a very localized affect - reducing the amount of radioactive iodine that gets to your thyroid gland, so reducing your chances of thyroid cancer years later. The other 99.99% of your body gets zilch, zip, zero, nada protection from the iodine. Your short term risks of radiation sickness or resulting death are unaffected by the iodine.
Yes I misstated what Iodine could prevent. Unintentional my omission was that iodine will only reduce the amount of radioactive iodine absorbed by the thyroid, and prevent thyroid cancer at a later date.
As far as radiation sickness, avoiding contact with the dust as much as possible will help prevent absorbtion. Keep inside in a well sealed area. After a few days, the dust will settle. If possible, bathe in non contaminated water. Although remember that water resources may be in short supply, and may be better served by saving for drinking.