Not so sure on an answer for your GMAT question -- would be good to check with your contact in admissions.
Regarding missing classes, that's not unheard of. If you can, try to avoid classes with a participation grade or many live presentations during seasons you anticipate having a heavy travel load. Fortunately, participation is often a more of tiebreaker for the curve grading in classes. Most HW submissions are due online, but for classes that call for a hard copy, you'd want to submit ahead or coordinate with someone in class to submit on your behalf. Another great option is that some classes let you sit in on another section if your schedule requires (e.g. If your thurs night class has a Saturday section, you can attend that when necessary, up to a cap).
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