Not to discourage you, but just a reality check: if you’re referring to top schools like Stanford, Chicago, MIT or CMU’s CS department, don’t take your score averages to mean that you might get in. Pretty much everyone who is applying has a score as good as yours (or better), and the college can only take 5%-8% of those - so that’s your % chance irrespective of scores. (CMU’s overall average acceptance rate isn’t that low, but it’s CS acceptance rate is as low or lower than Stanford’s, around 5%) Your ECs will definitely increase your chances (and you have some good ones in CS already, congratulations). But even then don’t count on them. Shoot for your dream school but have some solid second options (which could be equally good, a school like Grinnell for example, is excellent). (For example, my D’s scores were above the average for every top-10 school she applied to, and she didn’t get accepted to any.)
Also if you already plan to go to grad school, then which undergrad school you go to won’t matter as much as what you do during your undergrad.
You will not achieve fluency with courses in college, unless its your major and you really focus on it. But if you want to do a masters in Germany, for example, then take some German in college, and live in Germany for a couple of years where you can study the language in an immersive environment (much, much better) as you do your masters (Germany has some excellent masters courses, in English, and yes, they’re almost free). (My D’s hoping to do a masters/PhD program in Germany as well.)
No. And in fact you might find fulfilling the specific requirements of a minor too restrictive or difficult due to course scheduling conflicts. What I would suggest you do though is to take the AP German or French test – whichever one you want to study in college - and get a 5, so you can skip right to a more advanced level and then if you do want to get a minor you won’t have to take as many courses. My D is doing this right now, she’s a engineering major but will probably get a minor in another language (Chinese) because she was able to use her AP classes to get ahead and the requirements are easy to fulfill. She was originally going to minor in psychology but found that it was too difficult to schedule the particular courses she needed (her required engineering coursework is heavy and doesn’t have much flexibility), so she’ll just take the psych courses she’s interested in and won’t get a minor. You could use the same approach for language.