Couple of questions from a NOOB!!

you are never suppose to go under 1200 net calories a day. yes mfp wants you to eat back what you exercised off. you are in daner of going into starvation mode at anything below 1200 net calories a day. what is a net calorie? net calories are what you ate - what you exercised off= net calories.

From my experience, i would try and consume the cals which you need or your body will start to keep hold of the nutrients that you consume, this will keep the fat on, and make you very tired as thje nutrients will not be used as energy

There are a ton of threads on "starvation" mode. They can explain it much better than I, but no, you won't go into "starvation" mode. It can decrease your metabolism in the long run. It isn't hard to add in some extra calories with things like nuts, seeds, avocado, even a bit of cheese.

The second thing - MFP is set up to put you in a calorie deficit without having to work out. It suggests you "eat back" your exercise calories to keep you at a deficit, but not too large of a deficit. For example, if your base rate for calories is 2000, meaning you will not gain or lose at that number, and you select 1 lb a week, it will suggest you eat 1500 calories a day. That will create a 500 deficit. 3500 calories = 1lb. If you exercise and burn another 400, your are only netting 900 calories per day, giving you a deficit of 900.
Eating too little can cause a number of issues, including lack of energy and slower metabolism.

I promise you, I spent the first 80 of my last 86 or so days NOT LOSING WEIGHT. I stuck to my calorie goal, had no problem because I got so good at making low calorie meals! How is it possible for me to be consuming 200 calories less than my daily goal of 500 less and not lose weight? a 700 calorie deficit... not losing weight!

I was eating too few calories. My goal is 1690... I was eating in the 1400 range consistently and DID NOT LOSE WEIGHT. In fact, the few times I did have a momentary loss was after a random cheat day or a day I went over!

Eat those calories hon, or you might not lose weight at all! I worry that I may have lost muscle...

My suggestion is squeeze in a protein drink or add a glass of chocolate milk if you have to! Drink orange juice!

So what is more important? Eating your recommended allowance for fat and sugar or eating enough calories because all suggestions like nuts, cheese, and juice are high in fat or sugar.

So what is more important? Eating your recommended allowance for fat and sugar or eating enough calories because all suggestions like nuts, cheese, and juice are high in fat or sugar.

This is a good question - I think it's all about balance. I find that if I plan our my day ahead of time (it doesn't mean I can't change it, but at least I have a plan!) then I can see where I am coming in short, and can choose what extra foods to add to balance out my carbs/fat/protein macros.
I also don't get too bothered if I'm over a little bit for fat or protein or carbs, but if there is a big imbalance in one I will change my plan.
I do try to keep an eye on sugar and sodium. Most days I am over for sugar but as long as the majority of that is coming from unsweetened dairy or from fruit I don't worry there either.

That was the long answer - in short, I think calories are important, but try to make them healthy ones
By the way, I don't consider juice healthy, you are just getting the sugar and cals without any fibre.
My suggestions for extra cals are nuts, avocado, fruit, veggies, cheese (watch the sodium), brown rice, whole grain bread, dark chocolate (in moderation!).