A few questions about brushing my teeth

Does plax do anything spectacular, does it actually loosen plaque before you brush? How does it work exactly?

After I brush my teeth to get the taste of toothpaste out of my mouth I rinse my brush off then lightly brush my teeth again. This removes all the residual toothpaste out of my mouth, but I wonder if this is a bad idea. One of the reasons brushing is a good idea is that the fluoride ions interacts with calcium ions in your teeth and make the enamel stronger. Wouldn’t rebrushing my teeth remove all the fluoride ions?

Why is it that products like ACT fluoride rinse say you shouldn’t eat for 30 minutes after you use the rinse?