For your research questions: if you just started research this summer, you probably won’t have enough time to enter the Siemens Challenge. 3 months is not enough time to get any decent research done.
Intel, on the other hand, is doable. I have friends who became semifinalists after 5 months of research. It depends on a ton of factors, including luck.
Don’t do research because it looks “good”; do it because you are interested in the subject. If you like an internship better, then apply for the internship. It’s a lot easier to talk/write about interesting things (big boon for essays/interviews).