Fabric is 100% cotton and does not really stretch. Care instructions are to dry clean - only if you love it!
Gals with larger than a C cup, go for the Medium or Large. The general sizing guideline would be Small: 32-34" bust, Medium: 36" bust and size Large: 38" - 40".
You have some leeway because there is an elastic band in the back of the cami at the top. The waist flares out like a dolly-style top so don't worry about the waist measurement so much.