Also, food that I cook on it has a metallic-y taste. What can I do to fix both these problems?
Thanks in advance.
Oil breaking down during cooking most likely. It goes through a brown stage and then gets sticky brown. This isn't really a concern imho, but pretty common for a wok to make a paper towel dirty when wiped.
As to the metallic taste, I suspect two related things. Wok is not hot enough and liquid pooling in the bottom of the wok. On common western style stoves in the home there simply isn't enough heat generated to stir fry in the traditional manner. Instead, you have to cook the food in small batches and recombine at the end. Cooking in small batches lets the wok come back up to heat quickly and maintain a temperature for a good result. It's hot enough to cook the vegetables to a crisp tender stage and drive off any liquid they release--which is small amounts since you're cooking in small batches. If you have too much food in the wok, it can't come back up to heat fast enough, the food is too large of a heat sink. So the liquid released pools and boils steaming the food. This gives the metal of the wok an opportunity and method to impart the metallic flavor you're getting.