Welcome, it's great to have you. Always keep in mind: don't feed the troll!
In answer to your question: for the most part you only apply to get into the school. You don't go to medical school and "major" in anything. "Majoring" in medicine is called deciding on a specialty (which is accomplished during residency). However, there are certain schools that offer additional instruction in the form of MD/PhD, MD/MS, etc. Hope this helps.
No no no, because a troll can be cunning, subtle, a sleeper cell that puts in a great deal of effort into frustrating others. A tool is just a useless POS, a poor troll. A troll can be a tool, but not every troll is a tool.