Damage the throttle body adjustment screw

Hello colleagues, if the title explains my current situation, wanting to regulate the rpm of the engine, my engine was never the same after the shock I had, I started to move the screw of the throttle body, which seems to be plastic because it hurt The head of the screw and wanting to remove it with a screw extractor is not achieved.

Currently when I start the engine from cold it works at 2000rpm and normalizes at 1500rpm, the truth too much for an economic operation.

 

My question is can you remove this screw from the inside of the piece?

If I drill the screw to destroy it, that there is at the end of that screw, to avoid to damage it with the drill?

Is the throttle body of the pajero io compatible with any other mitsubishi model?