If your wine finished fermenting, and you won't be adding new sugar to sweeten it, sorbate will not be needed. If you plan to add some sweetness to the finished wine, sorbate will keep you from getting a new ferment going.
K-meta is short for potassium metabisulfite. Some people shorten it and just call it sulfites. You can buy it in powder form or you can use campden tablets if you have them available. It's the same stuff, just in tablet form. Sulfites will help preserve your wine, keep unwanted activity from starting, and reduce the possibility of oxydation.
Degassing is used to remove the carbon dioxide from your wine. When wine ferments, carbon dioxide is a natural by product. If it stays in your wine, it will be fizzy like soda. Since your wine is a year old, it may have already given up much of it's dissolved gas the same way a glass of soda will go flat over time. You can degas with vigerious stirring or with a vacuum device.