It is great you are looking at your option to USCGA in your Freshman year. And yes, you have loaded questions so let me try to answer them one by one.
First of all, welcome to SAF. This is a great forum and everyone on this forum have keen interest to help and have keen interest to learn. And there are few on this Forum who are veterans and have deep knowledge on the process, culture, Academies, and in the service. Much more depth than I. This is what I learned, initially as a non member following the Forum and recently joined the Forum since this January so I can interact to learn from others with specific questions for my DS. So I am also new to this Forum.
Having said that, I am not new to the military environment and not new to your awesome school. I graduated from Brooklyn Tech many decades ago. So let me speak from knowledge as an Alumn and about your majors and how that can help you position your App to the USCGA or any SAs. My DS ("Dear Son") received Appointment in early November to USCGA through Early Action and also to USNA, and attended West Point and USAFA Summer Seminars so we just went through the process past 14 months.
Brooklyn Tech is the high school version of MIT (actually bigger than MIT with 5,500 students from selected HS students in greater NYC). This is in curriculum, size, and student quality. My entering freshman class was 1,600 and 1,200 graduated, remaining returned to their district schools between freshman-sophomore years. Bronx Science is the high school version of CalTech, again for the same reason. Stuyvesant is the high school version of Stanford, again for the same reason. All of these schools are brilliant. Academies and top schools in the country know your school very well. Because so many fill their freshman class from these schools. I don't know the numbers attending top schools today, but from my class, I remember 6 attending Service Academies if not more. 25 got accepted to MIT, 15 to Harvard, 100+ to Cornell and more than half the class got accepted to NYU from a graduating class size of 1,200.
The schools you are applying to know Brooklyn Tech because they have very long history with Brooklyn Tech. In fact, Astronaut Karol Bobko (Ret Colonel) was Tech 1955 and USAFA 1959. He was the first graduating class of newly established USAFA and the first Astronaut from USAFA. He's in the Academy Hall of Fame at the USAFA. 4-Star Air Force General James E. Dalton is Tech 1949. He was the last graduating class from West Point 1954 to enter the Air Force Service by a commonly available cross commission to Air Force back then. Cross commission still available but not common.
Academies have long history with your school so they know your school Majors. I am carefully setting this up because I want you to personally challenge yourself with a major you can truly enjoy learning and not select one because it will look good! You never want to pursue things in life because others think it looks good! You do it because that's something you like to explore, take challenge, learn, and enjoy. But I will say this, the following majors may have the most relevance to the Academy curriculum. In addition to these Engineering Majors, you will take AP level core curriculum in STEM to supplement the New York State Regents requirement. Here are my suggestions on Majors I would consider at Tech and any from this list will give you advanced prep at any Service Academies:
Architecture (more relevance to USCGA)
Civil Engineering (more relevance to USMA)
Mechatronics & Robotics
If you take any of these engineering majors plus your required core STEM/APs, you should be very well ahead. I would say easily to Sophomore year level STEM ready at any SAs.
Early Action works early! You should start your App early August when the App opens up for USCGA. In fact, you can open your App by applying to AIM Program each summer. They take App until end of March each year. Once you finish the Preliminary App applying to summer, you will know the process. By attending AIM at USCGA you will learn the App process even better. You should complete all App components by early Sep. So get all your teachers' recommendations by June. You will need min 4 references plus guidance report. Don't wait until Sep to do you will be very busy then for other college Apps. Finish your PFE and DODMERB by Sep, even better if you can finish PFE this summer or by June. And work on writing your college apps in the summer.
Sports, take team sports and individual in combination. I found best combo for non buff kids to be in: Cross Country, Track, Swim, Gymnastics, Volleyball. You should have team sports (Varsity levels). You should make team Captain by Senior Year. You will have to be a good swimmer to attend USCGA and USNA. Tech has Swim pool so join Swim Team. But even for the other SAs, you have to know how to swim well if you want to pass the physical at the Academies.
You should also be in Scouting program. If too late to start to become an Eagle Scout then join Venture Crew to earn the Summit Scout Rank. That you can earn in 2 years. Apply and get selected to Boys State New York in Spring Junior Year. Join and take on leadership positions in school clubs you really can enjoy. Perform about 50-100 community service hours that are meaningful each year from now until Fall Senior year. My DS did 670 service hours in grades 9-11. Stick to all activities for 2-4 years, no less than 2 years. Deep quality activities in few important areas will help you and build you.
Academically, at Tech anything above 90 is stellar. 90 at Tech is like 96 at district schools. I know Tech doesn't rank but 90 at Tech should keep you within top 10-13% of the class. But work hard to earn your best grades overall. Most important at Academies is your ACT or SAT. So test well. Get all sections above 700 or above 30+ in all sections in ACT. I know that Tech average is 32 ACT and 1450 SAT and most students score 750-800 and 32-36 in Math sections at Tech, so you should test 1500 SAT and 33 ACT to be above your class average. These scores will likely get you an LOA (Letter of Assurance) if applying from NYC. Whether you get an LOA or not also depends on competitiveness of your district. Queens is very competitive, Brooklyn is less. So if you live in Brooklyn then you are more likely to get an LOA once your SAT/ACT hits the number above. USCGA and USNA only look at Math and English and USCGA also take your Writing. So do well in Writing. USCGA combined ACT average is 32 and 1400 SAT for Early Action and more likely the same for USNA if not higher for students applying from highly competitive districts like NY-3 and NY-6. USCGA select students at the national level unlike the other 4 SAs. So does not require Congressional Nomination but they cannot select all the best from the same district so you will be competing against your best in your district regardless.
You will be automatically considered for Scholar program at USCGA. But this is for students who don't make the selection to entering class but given a year to school and come join the following year entering class. So it's a prep school, usually for less academically competitive otherwise competitive applicants. Although your grandfather service in the Korean military is honorable, has no bearing in your application.
I think this loaded answer is more than enough for you to start prepping in the right direction. Good luck in your journey. Prepping for Service Academy from Freshman year is not too late. It's very good! Many committed and serious hopefuls start in 6 or 7th grade to begin preparing for Service Academy. My DS started in 6th grade when West Point and Air Force Academy reached out to him then. It will take you about 14-16 months to start and commit to Service Academy if you are successful. If not and become a re-applicant, it can take you 22 months to become a Cadet at an Academy. Good luck, stay focused, remain motivated, and enjoy the journey!