I think there is a misnomer with the term "high metabolism", people associate with weight loss. All it means it converting food into energy to maintain life, and a high metabolism would indicate an efficient system, meaning you'd burn almost all the food and store none of it as fat.
Yes, the number of meals DOES have an effect on the metabolism. The digestive system is like any other input/output system. Think about it. The smaller the portions of food eaten, the less work your body has to do to digest the food because and the more efficiently it can use food, hence (higher metabolism). If you ate 3 large meals, you're body would have a hard-time digesting that amount of food causing your insulin levels to spike and you would get sleepy, and if you did it for a lifetime, you could end up with Type 2 diabetes.
To keep a system in check, it needs to be consistant, so eating small portions less often and doing so slowly will guarantee that.