The corona is missing from this sketch, it appears as a non-uniform shape forther out than the chromosphere. The corona may be viewed when there is a total solar eclipse.
Nuclear reactions release more energy than normal burning.
Only a small amount of mass per second is needed to be converted into energy to allow the sun to shine for 10 billion years. The sun would have had to have been much larger in the past than it is now. Helmholtz's own calculation suggested that the sun could only be around for 25 million years, if fueled by this energy source. The sun spot cycle is 11 years. If no sunspots were seen in 1996 then there should be no sunspots in 2007.