Red wine, 18 degrees Celsius.
White & rosé wine, 7/8 degrees Celsius
Sparkling wines, 6/7 degrees Celsius.
These temperatures are for normal, every day wines. For aged white wines, serving temperature should be 2/3 degrees higher. Same for aged, complex red wines. Old vintage of classic method sparkling wine, a couple of degrees higher.
The correct serving temperature can be the difference between "I really enjoyed the wine" and "I didn't enjoy the wine at all"
A. Sulphites are organic compounds that occur naturally in grapes and many other fruits and vegetables. But sulphur dioxide is also added to wine as an anti-oxidant and anti-bacterial agent to prevent the wine from going off. The levels are extremely low, but some winemakers are trying to avoid adding extra sulphur dioxide, though this does run the risk of wines spoiling more quickly.