No - it is not really needed. Molasses (unrefined sugar) is a preservative in its own right. If you were to use an extra, it would tend to be sodium metabisulfite which admittedly is a source of Sulfur dioxide.
Sulfur is not removed from molasses. If you have seen molasses bottles that say "unsulphured" (old-fashioned spelling), it means that sulfur dioxide was not used in processing the molasses. Most molasses today is unsulfured.
One use of sulfur dioxide is as a food preservative (by killing bacteria).
Yes, sulfur dioxide (SO2) is often used as a preservative for its antimicrobial and antioxidant properties in fruits and wines.
Some foods are treated with sulfur dioxide as a preservative measure. It's not done as much as it once was, and for most people it doesn't appear to cause much of a problem... though a few people do seem to be allergic.
Sulfur dioxide is not in flour.
Sulfur dioxide followed by its hydration is used in the production of sulfuric acid.
A compound that is used to preserve fruit and produce an inexpensive acid is sulfur. Sulfur dioxide is often used to preserve fruit.
Only the sulphur dioxide is largely used (code E220 in EU).
No, they are two separate gases, with completely different properties. Sulfer Dioxide is found in things like car exhaust and contributes to things like acid rain. It's also used as a preservative for food. Its Chemical formula is SO2 Sulfur Hexachloride is another compound entirely. It is very hard to make and has few practical uses, outside of the chemists lab that is. Its Chemical Formula is SCl6
chromatography
Sulfur dioxide
During Photosynthesis carbon dioxide is used and oxygen is released. In chemo-synthesis oxygen may be used but it releases Sulfur dioxide. Example of chemo-synthesis are sulfur bacteria.