before the oil temp indicates an excessively high value. In any case immediate action should be taken if the oil temp is observed approaching the redline ( ie full rich mixture and increase airspeed).
Yes. Though I agree with this, by the time your got the engine to this point either you have damaged it, or you are about to.
Enrichen mixture, yes, increase airspeed , yes, but not to the point of a dive with the power off, that will shock cool the engine, which is the last thing you want to do with an engine that hot.
The important thing is to not get yourself there in the first time. Parachuting pilots are usually thoroughly briefed about treating engines gently in this regard.
If the aircraft you are flying has a CHT (if it has cowl flaps, it is required to), watch it as you change power. If you can see the pointer move at all, you're changing power too quickly. If the aircraft you're flying has an "aftermarket" CHT, and not a probe on every cylinder, be aware that the probe might not be installed on the hottest (or coolest) cylinder. Use that reading with caution...