Oh very dear.
1 & 3 are complete rubbish but number 2 is actually correct.
In the event of a release of radioactive Iodine the best way to protect your thyroid is to 'load' it with non-radioactive iodine. I used to work at a nuclear power station and, in the event of a nuclear incident everyone would be issued with potassium iodide (KI) tablets to load the thyroid and minimise the risk of absorbing radioactive iodine-131.
Here is the Health Protection Agencies/National Radiation Protection Board documentation on Iodine usage to protect against ingestion of radioactive iodine:
clickey. Scroll down to the bit on Iodine tablets near the bottom of the page for dosage recommendations.
The body alkalizer thing is hilarious (the bit about the effects of drinking distilled/de-ionised water for long periods is actually not far off the mark though). I was more concerned about the Stabilized Oxygen product on the same page though. He appears to be selling a type of bleach (Sodium Chlorite) for people to drink.