Vinegar is used as the solvent in which ordinary table salt it will be mixed in. Since vinegar is over 90% water, salt will dissolve into it as any ionic solid does when mixed into an aqueous solution. The only reaction is entropic as the solid dissolves; disspating minute amounts of heat which is only noticeable when done large scale.
Salt and vinegar can react to form hydrochloric acid. These two substances, known in chemistry as "sodium chloride" and "acetic acid" respectively, can be used in school educational experiments to clean a blackened penny. Even though hydrochloric acid is known to be highly dangerous and potent, the product of this mixture isn't pure enough to be considered harmful.
Yes, in a positive way. Together they make an excellent cleaning agent for glass coffee pots and for kitchen and bathroom sinks. A mixture of 8 ounces of water and one half teaspoon vinegar will clean most anything glass within reason, and will wash grease and odor from drain traps.