Motorcycle Questions? Ask a Mechanic.
Overheating can do different types of damage. It certainly isn't good in any way. The long term effects are typically hardened gaskets and seals that begin to leak. It can cause piston rings to lose their tension which will allow oil to bypass, compression to decrease, and likely cause the engine to begin to smoke due to oil bypassing them.
There really isn't anything to do other than changing the fluids. I would suggest doing the plugs as well as the ceramic can develop cracks.
The white dust is the oxide layer that naturally forms on the aluminum being "cooked" off the base metal. It will naturally reform over time. Do not use any type of strong cleaning agents on the engine for a while. When the oxide layer is stripped away the aluminum is very susceptible to staining.
I hope this helps. Please let me know if I can be of further assistance. Also, please leave a positive rating for my service today. Thanks, P.J.