Okay, I'll just put in what I think here.
She's from a shelter and was one of many other cats. She's probably learnt that if she doesn't eat everything in one sitting, she will never get enough. With time, this passes as she adjusts to being in a forever home. You may need to reduce the size of the meals and feed her more often if she does vomit after gorging.
Wet food is better than dry food because it is richer than dry and contains a lot of nutrients. This is especially good for kittens and cats that have missed out on nutrients due to poor diet. However, by the same token, if your kitten or cat is not used to food rich in nutrients, diarrhoea can occur. So it's best to start with dry food and gradually introduce wet food. This can be done by slowly adding small amounts of wet food ever increasing to their diet. And vice versa for the introduction of dry food. This can be done in separate bowls or in the same bowl but dry food tends to absorb moisture from the wet food.
And if you do feed your cat or kitten wet food only, this can lead to dental problems as their teeth are not rubbing against anything, nor are they doing as much work as they would in the wild. An occasional chicken wing with the bone, (UNCOOKED!), can be given as a treat to encourage chewing and gnawing action that would occur in the wild.
You can decide to have dry food as a treat for your cat. Nothing wrong with that.
Also, just because it's higher in carbohydrates than wet food, it doesn't neccesarily result in weight gain as cat's metabolisms and physiological make up is different to ours. There are other factors to weight gain like lack of excercise, high nutrient intake and so on.
I think I've covered all of it.