I wouldn't consider it rude to call/email for an update, given that it's been a week. Holidays can throw things off a bit, so they might just be running a bit behind. But the reasons you've given are completely legitimate concerns.
All of those dates are within the next couple of weeks so I don't think its rude to call to follow up. It is common knowledge that last minute airfare can be outrageously expensive and I'm sure they will understand your desire to plan immediately for the sake of your budget.