There will be a lot of algebra in statistics.
I was a math major. As a graduate student I took one single course that was not a math course. It was econometrics. There is a lot of math, and specifically a lot of linear algebra (ie, matrices) in econometrics. I still remember taking a couple of Saturday’s to review linear algebra in order to fully understand econometrics and to be able to handle the class, and this was as a math major.
My recommendation would be to put a lot of effort into the class while you are retaking algebra 2. You might want to consider getting a tutor also or asking the teacher for extra help. You want to make sure that you fully understand the concepts.
With regard to precalculus, there is a big difference between “passing” and “mastering”. In my experience people who are very strong in precalculus tend to find calculus straightforward. I have heard that people who have struggled in precalculus can find calculus to be very tough. Precalculus is an area where being very solid can help you in the future (assuming that you will need to take calculus at some point).
Classes at Stanford go very quickly. CMU is also an academically demanding university. I am not sure whether I would apply to either with a 3.3 GPA. The same might be said for U.Florida and UIUC. You should make sure that you have a couple of solid safeties.