i’m applying to rice as well!
i would say to apply as a chemistry major because the rice writing supplement asks you why you’re applying to your intended field of study. it’ll be hard to answer that if you don’t have a field of study 
there are definitely going to be a lot of people who apply with way worse stats/ECs than you. keep in mind that thousands of kids from Houston ALONE apply, and very very few of them are actually qualified or actually have experience in their academic interest like you do. i’d put your chances more in the 35-45% range. make sure and mention your difficulties sophomore year (either have your counselor mention it in your counselor rec, or put it in the Additional Info section). and definitely work hard on your essays–personal character is a huge factor for rice. showing interest via interviews, email correspondence, or campus visits (if possible) will boost your chances too.
here’s my chances thread: http://talk.collegeconfidential.com/what-my-chances/1808459-chance-me-for-emory-northwestern-uchicago-and-some-schools-in-the-northeast-will-chance-back.html#latest
best of luck!