that's lame that there is no space for two majors. Extra points to Cornell for doing that much.
Yes, they'll see it on your transcript. I was all dis-heartened about some of the limitations of the forms I filled out, and then decided that they created the forms and were probably prepared to deal with the slight discrepancies that may be caused by the lack of pertinent details.
Re: Activities. If they don't diferentiate, put in whatever you've got. They didn't ask, so I think you should be able to put what you feel is most pertinent and/or shows you in the best light.
I don't know what to say about your tiny two-character field. Just slap in a one? how would it average out? .5 rounds to 1.....