That depends on how much power/boost you want to add.
Very generally speaking, you can run up to ~5 PSI on a stock engine. If you want to make more serious power ( run higher boost ), you need to lower the compression ratio ( to keep the engine from blowing itself apart ) and beef up the internals ( pistons, rods, etc ) with forged internals to be able to handle the additional stress of forced induction.
Well it all depends. It depends on how many miles are on your old engine. If you have any weak points anywhere, putting more pressure to it will cause it to fail early. You may not harm anything or you may find it quickly. It just depends on the condition of the engine
Yes, the internals need to be strengthened or it will blow itself apart with the extra pressure.
Yes. New pistons, new rods, new crank, new cam
Do i need to do any internal engine work before i install a turbo system