Hi lemonmelon,
First off, a 730/Q50 is an outstanding Score, so you can comfortably apply to any Business Schools that interest you. As such, a retest is almost certainly NOT necessary. Most Schools do not care much (if at all) about an applicant's IR Score, so you have likely have nothing to worry about with an IR5. Depending on the Schools that you plan to apply to, you would likely find it beneficial to speak with an Admissions Expert about your overall profile and plans. Those Experts should be able to answer your Admissions questions and help define the specific areas of your profile that could use some improvement. There's a Forum full of those Experts here:
https://gmatclub.com/forum/ask-admissio ... tants-124/While the two situations that you faced on Test Day likely impacted your performance, the fire alarm wouldn't have had as much of an impact as you might think. Since the fire alarm first occurred at the END of the Verbal section (after you had already taken the Quant section) - and you only had 1:40 for the last 2 questions - it was likely that you were going to get one or both of those questions wrong anyway (if they were both SCs, then you would have probably needed 2.5 minutes to correctly answer both - and if either was a CR, then you would have needed even more time than that). Thus, the impact to your Score would have probably been limited to just the 'penalty' for not answering the questions - and that was likely not more than 10 - 20 points at MOST (depending on how you were performing up to that point in the section). This is meant to say that you would probably have earned a V40-V41 regardless of the fire alarm going off.
All things considered, you've got an outstanding GMAT Score right now, so you would likely be fine sticking with this Score and applying to any Program that interests you.
GMAT assassins aren't born, they're made,
Rich