Um the word gluten might be a hint its high in gluten! YES! Gluten Flour is specifically gluten. Its like maximum amount of gluten possible. You use gluten flour to make baked goods stretchier ect. YES
It's in the middle of the range of flour, that's why it's all purpose. It will work for anything, just not as well as cake or whole wheat that are at opposite ends of the range.
No. High gluten flour is used for baking breads, where a more chewy texture is desired. Lots of mixing and kneading "works up" the gluten in bread dough to create that chewiness. For cakes, which...