What everyone else has said is very good advice- it is very early to start thinking about college- but as a current high school senior who just went through the process, I might be able to relate to you just a little bit more.
With regards to the finance stuff, I don’t really know much about it (I was incredibly fortunate to not have to apply for fin aid because of my parent’s situation), but I would start having discussions early, as other posters have said. It is better to be prepared.
With regards to preparedness for these top, “lottery”-type schools, my honest advice as someone admitted to GTown/applying to Ivies, and seeing multiple of my friends admitted to HYPSM-type schools, is that there is no one-size-fits-all way to get into these top schools. What I believe the Ivies/Stanford are looking for are genuine, authentic kids with exciting stories, strong leadership abilities and a zest for learning, in addition to top grades/test scores. Based on that, I can give you a few tips to put you on the right track (without stressing you out too much):
-While you don’t want to be freaking out about GPA yet, it is wise to do as well as you can from the beginning, as classes will only get harder as you move through high school. Having a “buffer” from 9th/10th grade for your GPA can help when you start to move into APs, etc.
-Choose the most rigorous course options when available, and when it makes sense for you. For example, if AP Physics is offered, but you hate math, don’t take AP level! I am not a math kid, but I am taking the highest level history courses available in my school. Know your intellectual strengths.
-Each school has slightly different requirements for # of years per subject, but I would recommend if possible getting four years in each (perhaps not language if you really don’t like it, but the top schools will look for at least 3 years of language). You don’t want to box yourself in too early.
-By the end of sophomore year, take a practice ACT and a practice SAT. Identify which one felt easiest/you enjoyed (if you can enjoy a standardized test) the most, and study for that. I would recommend taking it 2-3 times (until you settle on a score you are happy with). It is my personal opinion that it is MUCH better to have your standardized testing complete by the end of junior year, so you are not preocupied with it during college admissions season.
-The schools you are aiming for require/“strongly recommend” two SAT IIs. These are subject tests, and I would recommend taking them immediately after you finish the relevant class. For Ivies/Stanford, you really should aim for at least a 700, preferably higher.
-Don’t choose extracurriculars based on whether they look good for college. Find activities that really excite you, so it no longer feels like just another task to complete. Whether it’s theatre, sports, a job, get involved and get involved deeply.
-Take initiative with activities/projects in the community. From my personal observations of where my friends get admitted, the ones who are successful with the top colleges have not waited for opportunities to land in their lap- they have gone out and taken them.
-Spend your summers doing things that align with your interests. Do you like languages/int’l relations? Look at doing NSLI-Y. If you’re interested in science, try to find internships/research opportunities at local universities, which can often be found by emailing professors.
I hope these tips will help you as you prepare to enter high school. While I tried to give more concrete advice, I do want to emphasize that what the other posters above said was right- you want to ENJOY high school and milk it for all it’s worth, rather than just seeing it as the path to college.