Median rhomboid glossitis- can it change from light to dark and back again? Should I worry? Woman age 34 with full set of dentures.

Proper diagnosis. Has your dentist made a definitive diagnosis of median rhomboid glossitis? If not, it should be looked at by your dentist for other possibilities. If it has been definitely diagnosed, there is no need for concern as this does not neet treatment. However, if there is burning, you might benefit from an antifungal medication. See your oral surgeon for advice.
yes. This is a benign condition which does not require any treatment beyond brushing your tongue.
Chronic C. albicans . Chronic c. Albicans infection treatment consists of identifying and managing predisposing factors . Solution application of topical anti fundal agents like nistatin .This lesions persist for many years but do not usually involve other anatomical sites . Many patients are smokers , dentures wearers . Treat site and rinse denture with nistatin .
Glossitis. You should be placed on anti fungal agent. You should be evaluated and see what the source of the problem is. Nothing to worry about.