Hi sittmo,
Business Schools generally don't care if you retake the GMAT, so you likely have nothing to worry about regarding whether you cancel this first Official Score or not. To answer your immediate questions:
1) NO - you do not need to cancel your first Official Score before taking the GMAT for a second time.
2) YES - you can pay to reinstate a cancelled score.
3) When you take the GMAT, you have the opportunity to send your score to up to 5 Schools. If you did not choose Schools at that time, then your Official Score Report will not be sent to anyone (and you will have to pay a 'per school' fee to have your scores sent later on - currently that fee is $28 per School). You can send multiple scores to the same school, but again - they likely won't care if you do - and they'll likely consider your highest score when evaluating your application. If you have deeper questions about how an individual School would handle that situation, then you should contact the School directly and ask.
Since you're clearly planning to retest, it might help to know how you studied before (so that you can make the necessary adjustments and score higher next time:
Studies:
1) How long have you studied?
2) What materials have you used?
3) How have you scored on each of your CATs (including the Quant and Verbal Scaled Scores)?
4) How did you score on the Official GMAT (including the Quant and Verbal Scaled Scores)?
Goals:
5) What is your goal score?
6) When are you planning to take the GMAT?
7) When are you planning to apply to Business School?
8) What Schools are you planning to apply to?
GMAT assassins aren't born, they're made,
Rich