What are my options for pursuing two degrees in college? What is a double major, and is it applicable to me?

A double major basically amounts to getting one degree in two subjects, so if you did one you'd have a BS in Computer Science and Economics/Statistics. But to do a double major, both majors need to be offered in the same internal college—you can't do a double major where one degree is in the College of Engineering and one is in a College of Arts & Sciences, for example. So you'd need to find schools that have Economics/Stats and CS in the same college—there are plenty that do, like Cornell for example, but it's something to keep in mind. But if you want to go deeply into two subjects, that would be your best and most efficient option. Pretty much any school will let you do it aside from like, Princeton, I think.

Otherwise, if the programs you want in separate college, you then need to do what's called a dual degree, which is where you get two separate degrees from separate undergraduate colleges (in the same university) in each subject. So you'd have two B.S.'s, one in Econ/Stats and one in CS. The difference is that you'd have to do all the general requirements for each college you're in (so all the Engineering requirements and all the Arts and Sciences requirements if you took CS in Eng and Econ/Stats in A&S), and you might need to spend 5 years in undergrad rather than 4.

If you decide to do a degree in Econ or Stats and then a Masters in CS, what you'd need to do is make sure you take all the basic CS courses anyway that would give you a grounding in the subject. Because if you just did Econ or Stats, you'd probably be lost in a Masters program.