how to change .exe file icon?

Stardocks Icon Developer will handle that for ya.

or better yet, go here......

http://www.howtogeek.com/75983/stupid-geek-tricks-how-to-modify-the-icon-of-an-.exe-file/

^^ Yes. Resource Hacker can be used to change icons, menus, dialog boxes, text strings in an EXE, DLL or other system files. If the OP is not familiar with Resource Hacker, he can check out following tutorial to learn 

All About Resource Hacker in a Brief Tutorial, Ultimate Windows Customization Tool

you can also open the .ip file by changing the .ip to .zip and opening that file with winzip or any zip program.