Any tips for college applications/admissions related anxiety?

You are worrying for no reason.  Almost anyone can get into a college; its not life or death.  Paraphrasing Lloyd Blankfein, you are applying to college. You are not going to Omaha Beach in a Higgins boat. 

Realize you're worrying for nothing and make it all less complicated.  The time for lots and lots of research is past.  You just need to pick 5-6 schools that meet your criteria in terms of size, location, climate, cost, and campus culture.  Pick two each of "reach, target, and at least one safety).  You can use your schools Naviance program or websites like Niche and BigFuture to see data on the GP and test scores or admitted students.

You should only apply ED to one school and only if that is your dream school and you'll never regret going.  Just one.  If you are apply to schools with rolling admissions, get those in sooner than later.

Most large universities are going to look at your GPA and SAT/ACT and make a decision. Your essays, ECs, and recommendations may only come into play if you are  on the edge in terms of academics or if you are apply to very selective universities.  

Make a list of tasks that need to be done and start knocking them out.  

1.  Ask ASAP for your letters of recommendation if you haven't already.  

2.  Start and save your Common App.  This is used by a huge number of universities and you need to get the data into it.  Most of it isn't hard, but it takes time and you may need to look up dates or some details.

3. Ask a favorite teacher, guidance counselor, or parent to read your essay(s) and give you comments.  Even professional writers get other people to help with revisions.

Many people stress eat and you life is really stressful, so not a surprise. The thing is that the snacking and comfort food aren't actually helping your body or brain to handle the stress.  Ask your parents to help by limiting snack food, sweets, and carbs in general.  Try a guided meditation podcast to help you sleep and or relax (tons are available) and make getting some type of exercise a daily goal.  Exercise and sleep will help you hand the stress better. 

First, your college applications should include ONE Backup, sure-thing admission, as disappointing, but can allow transfer into a different school a year later.

That means you are in high school now, and will be at a college or university of some sort.

You will apply to multiple schools, have exams, essays, grade submissions, interviews, applications for financial aid, and other things ahead of you.

You are NOT accepted to any school now, other than your "sure thing".

If you do not get an offer of admission to a school, you are in exactly the same position- Not accepted. Nothing is lost. Every offer is a win.

Therefore, everything to gain, nothing to lose.

This is a perception. All of your anxiety and stress is self-imposed.

If you get an offer of admission to a better school, it means you deserved admission to that school. If you do not get an offer of admission to a better school, then you did not deserve admission. All will be as it should be, regardless of the amount of stress and anxiety.

Movie "Bridge of Spies", Tom Hanks as James Donovan, the lawyer, and Mark Rylance as Rudolf Abel, the Russian spy.

James Donovan: "I have a mandate to serve you. Nobody else does. Quite frankly, everybody else has an interest in sending you to the electric chair."

Rudolf Abel: "All right"

James Donovan: "You don't seem alarmed." 

Rudolf Abel: "Would it help?"

You are Rudolf Abel in this analogy. But, it is not even as serious a situation.

If you do not get an offer, do they require you to get 30 lashes and 30 days in solitary confinement? No. You get a "no thank you notice". It isn't a writ of execution.

You can take all of the non-acceptance letters, tie a ribbon around them, and play Fetch with a dog.

As a university professor for the last 22 years my advice is relax! Look, you’re obviously a good student and you WILL go to college. Don’t get overly caught up in any quest for “the best university.” I promise you that wherever you go you’re going to have a fantastic experience, make great friends, gain incredible memories and go on to have a career and life, and you will honestly NEVER again think about the application process or your essay(s) you wrote. And when it comes to the biggest or most prestigious universities there are so many factors that go into the vetting and selection process that it rarely ever comes down to anything you can control like the essay or whether you should’ve done one more volunteer activity or played in the band your freshman year. Go with the flow! Enjoy your senior year as much as you can; you’ll never have that opportunity again, so don’t waste it consumed with anxiety about your next phase of life.