In an interview, the interviewer tends to ask if you've got any holidays planned, just tell them that you're going abroad then. If they like you and your interview goes well they won't hold that against you. As for your graduation, don't mention that in the interview, if you get the job you'll be entitled to a certain number of days holiday. So if you get the job, maybe a week before tell your manager you need the day off as it's your graduation.