No, a 45w adapter won't provide sufficient power for a 60w MacBook Pro to reinstall OS X.
No, a 45w adapter won't provide sufficient power for a 60w MacBook Pro to reinstall OS X.
Even when the Macbook uses more power than the charger provides, it shouldn't cause issues as long as the battery isn't entirely drained. If it requires more than the 45W the charger can supply, it will simply draw the surplus from the battery. It's best to keep the battery fully charged. Still, a charge of around 30% is acceptable.