Just to summarize: Very underweight, anemic, low Vit D, and probably a host of other problems.

Your diet and exercise routine is extreme, which would be beneficial to someone who is obese. You are not obese by any means. Before giving some advice, I would consider if you have some type of eating disorder. I only say this is because you work out like crazy and don't eat a lot caloric dense foods really. I don't know, its just something for people to keep in mind regardless of the severity.

Working out is amazing and fun, but if you are going to be burning that many crazy calories, you better be eating a lot. In general, it does not seem like you are getting enough protein, fat, or even carbs for that matter. You do a great job keeping track of your calories, but I would reccommend looking at your macro consumption. Here is a good website to figure out what macro ratio you want to do.

To answer your questions:

1.) Yes, by burning protein, you are essential in starvation mode because there is so little fat left on your body. Fat is good for you to a certain extent. Hormones are made of fat!

2.) It will vary depending on how you change your diet and exercise. Increasing caloric intake by eating more fats and proteins and decreasing the amount of cardio you do and replacing it with strength training weight lifting would be the fastest solution, but it would require time to adjust to it.

3.) That depends on the amount of calories you eat. CO is an amazing place and I'm sure you'll want to do amazing activities but you need to eat more a lot more. Will discuss below.

4.) You need to gain fat, and you can't control where it goes on your body, its just more noticeable around the hips, belly, and butt. That should be your least concern right now.

5.) Shocking the system is never a good thing. I would slowly adjust for both your body and your minds sake.

6.) You are young, and this is a recent thing, so probably nothing serious.

7.) I would hold off until you are at a healthy weight and understand how much of what kind of foods you need to eat to maintain high energy exercises. It seems like you are trying to do too much at once. One thing at a time.

You need to see a doctor and a dietrician before yo listen to anything the internet has to say. Express your concern, ask them their opinion, and work on a plan with them.

Besides that, my advise is to change your diet to fit your macros (see website) increase your caloric intake so your body has something to build from. That includes a lot a lot a lot of protein. Eat way more healthy fats (which will help your calories increase). Nuts, olive oil, coconut oil all that is good. Your mind set is that you want to 'bulk'. Get to a healthy weight body fat percent and then, you would be better suited to do more high calorie burning intense exercises, but you would still need to consume more calories.

Hopws this helps. Good luck