Hi BrodtandBread,
I like the basic timeline and structure of this plane - you've clearly thought it through. Studying for the GMAT before you get into the routine of a full-time job is also a smart idea.
If you're not going to take the GMAT until your Senior year though, then I have some issues with your current studies. I'm going to assume that you're on a 4-year plan to graduate. Since you're a Sophomore now, you're at least a year away from 'Senior year.' If that's true, then you might be starting your GMAT studies a bit too early.
I say all of this because I don't think that it will take you over a year to study for the GMAT. If you're consistent with your studies, then you'll likely hit your "peak" in 3-6 months, so really getting into those studies now would NOT mesh with your overall timeline. Since a GMAT score is "valid" for 5 years, if you took the GMAT in 3 months, then you'd have a shorter "window" to apply to Business School later on (before your GMAT score expired).
As far as your other questions are concerned, your GPA and Undergrad Degree should be fine - although those are really questions for Admissions Experts. You would need to have an actual GMAT score and your work experience would need to be better "defined" before any of them could assess your chances at getting accepted.
GMAT assassins aren't born, they're made,
Rich